【iOS】计算器实现

仿写iOS的计算器，使用了MVC模式和masonry库。

绘制界面

1. 循环建立button，统一设置属性，添加约束。
2. 将括号按钮的tag设成100+，运算符按钮的tag设成200+，数字按钮的tag设成300+，用于之后分类。
3. 设置不同按钮的颜色。
4. 将AC，等于和小数点这种特殊按钮赋给mainView的属性。
5. MainView声明一个数组属性，将除上面三个特殊按钮之外的按钮全部添加到数组里。
6. 在按钮上方添加一个UITextField，关掉它的用户交互。

MainView.h

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface MainView : UIView

@property (nonatomic, strong) NSArray* operArray;
@property (nonatomic, strong) NSMutableArray* buttonArray;

@property (nonatomic, strong) UITextField* calculation;

@property (nonatomic, strong) UIButton* ACButton;
@property (nonatomic, strong) UIButton* equalButton;
@property (nonatomic, strong) UIButton* pointButton;

- (void) initView;

@end

NS_ASSUME_NONNULL_END

MainView.m

#import "MainView.h"
#import "Masonry.h"

#define SIZE 85

#define CalculationWidth 375

@implementation MainView

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
}
*/

- (void) initView {
    self.backgroundColor = [UIColor blackColor];
    
    [self creatOperArray];
    self.buttonArray = [[NSMutableArray alloc] init];
    
    self.calculation = [[UITextField alloc] init];
    self.calculation.backgroundColor = [UIColor blackColor];
    self.calculation.textColor = [UIColor whiteColor];
    self.calculation.textAlignment = NSTextAlignmentRight;
    self.calculation.font = [UIFont systemFontOfSize:60];
    
    self.calculation.userInteractionEnabled = NO;
    
    [self addSubview:self.calculation];
    
    [self.calculation mas_makeConstraints:^(MASConstraintMaker *make) {
        make.bottom.equalTo(self).offset(-600);
        make.width.equalTo(@CalculationWidth);
    }];
    
    for (int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; j++) {
            UIButton* button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
            button.titleLabel.font = [UIFont systemFontOfSize:42];
            button.layer.cornerRadius = SIZE / 2;
            
            [self addSubview:button];
            
            [button mas_makeConstraints:^(MASConstraintMaker *make) {
                make.bottom.equalTo(self).offset(-(70 + (SIZE + 15) * (i + 1)));
                make.left.equalTo(self).offset(3 + (SIZE + 15) * j);
                make.size.equalTo(@SIZE);
            }];
            
            if (i == 3 &amp;&amp; j < 3) {
                button.backgroundColor = [UIColor grayColor];
                [button setTitle:self.operArray[i + j + 1] forState:UIControlStateNormal];
                [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
                button.tag = 100 + j;
                if (j == 0) {

                    _ACButton = button;
                } else {

                    [self.buttonArray addObject:button];
                }
            } else if (j == 3) {
                button.backgroundColor = [UIColor colorWithRed:251.0f / 255.0f green:151.0f / 255.0f blue:15.0f / 255.0f alpha:1];
                [button setTitle:self.operArray[i] forState:UIControlStateNormal];
                [button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
                button.tag = 200 + i;

                [self.buttonArray addObject:button];
            } else {
                button.backgroundColor = [UIColor colorWithRed:0.2 green:0.2 blue:0.2 alpha:1];
                NSString* title = [NSString stringWithFormat:@"%d", j + 3 * i + 1];
                [button setTitle:title forState:UIControlStateNormal];
                [button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
                button.tag = 300 + i * 3 + j;

                [self.buttonArray addObject:button];
            }
        }
    }
    
    for (int i = 0; i < 3; i++) {
        UIButton* button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
        button.titleLabel.font = [UIFont systemFontOfSize:42];
        button.layer.cornerRadius = SIZE / 2;
        [button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
        
        [self addSubview:button];
        
        if (i == 0) {
            [button mas_makeConstraints:^(MASConstraintMaker *make) {
                make.bottom.equalTo(self).offset(-70);
                make.left.equalTo(self).offset(0);
                make.width.equalTo(@(SIZE * 2 + 15));
                make.height.equalTo(@SIZE);
            }];
            [button setTitle:@"0          " forState:UIControlStateNormal];
            button.backgroundColor = [UIColor colorWithRed:0.2 green:0.2 blue:0.2 alpha:1];
            button.tag = 310;

            [self.buttonArray addObject:button];
        } else {
            [button mas_makeConstraints:^(MASConstraintMaker *make) {
                make.bottom.equalTo(self).offset(-70);
                make.left.equalTo(self).offset(200 + (SIZE + 15) * (i - 1));
                make.size.equalTo(@SIZE);
            }];
            if (i == 1) {
                [button setTitle:@"." forState:UIControlStateNormal];
                button.backgroundColor = [UIColor colorWithRed:0.2 green:0.2 blue:0.2 alpha:1];
                button.tag = 311;

                self.pointButton = button;
            } else {
                [button setTitle:@"=" forState:UIControlStateNormal];
                button.backgroundColor = [UIColor colorWithRed:251.0f / 255.0f green:151.0f / 255.0f blue:15.0f / 255.0f alpha:1];
                button.tag = 400;

                _equalButton = button;
            }
        }
    }
}

- (void) creatOperArray {
    NSArray* array = [[NSArray alloc] initWithObjects:@"+", @"-", @"×", @"÷", @"AC", @"(", @")", nil];
    
    self.operArray = array;
}

@end

添加事件

1. MVC模式要求我们在MainViewController里实现并添加事件。
2. 我们在MainViewController例调用MainView的属性，为AC，等于和小数点这种特殊按钮单独添加事件。

[self.mainView.ACButton addTarget:self action:@selector(pressAcButton:) forControlEvents:UIControlEventTouchUpInside];
    
[self.mainView.equalButton addTarget:self action:@selector(pressEqualButton:) forControlEvents:UIControlEventTouchUpInside];
    
[self.mainView.pointButton addTarget:self action:@selector(pressPiontButton:) forControlEvents:UIControlEventTouchUpInside];

3. 遍历MainView中储存普通按钮的数组，为它们添加一个总的事件。

    for (UIButton* button in self.mainView.buttonArray) {
        [button addTarget:self action:@selector(pressButton:) forControlEvents:UIControlEventTouchUpInside];
    }

4. 在这个总事件里，使用按钮的tag值进行分类，调用不同的事件。

- (void) pressButton:(UIButton*)sender {
    if (sender.tag / 100 == 1) {
        [self pressBracButton:sender];
    } else if (sender.tag / 100 == 2) {
        [self pressOperButton:sender];
    } else if (sender.tag / 100 == 3) {
        [self pressNumberButton:sender];
    }
}

5. 实现这些事件。

限制输入

在一定程度上限制用户的输入，保证算术式的正确。

1. 为每种按钮设置BOOL类型或NSInteger类型的属性，用于判断此按钮是否生效。每次用户触发点击事件后，先通过这些属性判断此次点击是否有效。若有效，则输入新数据；若无效，则跳过。

@property (nonatomic, assign) NSInteger rightBracLimit;
@property (nonatomic, assign) BOOL lefBracLimit;
@property (nonatomic, assign) BOOL OperLimit;
@property (nonatomic, assign) BOOL NumLimit;
@property (nonatomic, assign) BOOL pointLimitByNum;
@property (nonatomic, assign) BOOL pointLimitByOper;
@property (nonatomic, assign) BOOL OperLimitJJ;

2. 初始化这些属性，每种按钮在开始时是否有效是固定的，我们只需要将它们列出来。

// 设置按钮初始限制状态
    _rightBracLimit = 0;
    _lefBracLimit = YES;
    _NumLimit = YES;
    _OperLimit = NO;       // 乘除
    _pointLimitByNum = NO;
    _pointLimitByOper = YES;
    _OperLimitJJ = YES;  // 加减

3. 某个按钮的点击事件生效后，每种按钮是否有效也是固定的，我们一样将它们列出来。（以数字按钮为例）

- (void) pressNumberButton:(UIButton*)sender {
    if (self.NumLimit) {
        NSString* oldCalculation = self.mainView.calculation.text;
        NSString* newChar = sender.titleLabel.text;
        NSString* newCalculation = nil;
        if ([newChar isEqual:@"0          "]) {
            newCalculation = [NSString stringWithFormat:@"%@0", oldCalculation];
        } else {
            newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
        }
        
        self.mainView.calculation.text = newCalculation;
        
        // 设置按钮限制状态
        _lefBracLimit = NO;
        if (_rightBracLimit < 0) {
            _rightBracLimit = -_rightBracLimit;
        }
        _OperLimit = YES;
        _OperLimitJJ = YES;
        if (_pointLimitByOper) {
            _pointLimitByNum = YES;
        }
    }
}

4. 右括号和小数点的限制比较特殊。

右括号使用NSInteger类型，记录输入左括号的数量。输入一个左括号，我们是这个属性值加一，输入一个右括号减一。我们限制只有这个属性的值大于0，点击才能生效。如果输入某个非右括号的符号，我们将这个值改为负数以限制错误输入。（下为括号的点击事件）

// 处理括号
- (void) pressBracButton:(UIButton*)sender {
    if (sender.tag == 101) {
        if (_lefBracLimit) {
            NSString* oldCalculation = self.mainView.calculation.text;
            NSString* newChar = sender.titleLabel.text;
            NSString* newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
            
            self.mainView.calculation.text = newCalculation;
            
            if (_rightBracLimit < 0) {
                _rightBracLimit = -_rightBracLimit;
            }
            _rightBracLimit++;
            _OperLimit = NO;
            _NumLimit = YES;
            _OperLimitJJ = YES;
            
            _pointLimitByNum = NO;
            _pointLimitByOper = YES;
        }
    } else {
        if (_rightBracLimit > 0) {
            NSString* oldCalculation = self.mainView.calculation.text;
            NSString* newChar = sender.titleLabel.text;
            NSString* newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
            
            self.mainView.calculation.text = newCalculation;
            
            _rightBracLimit = _rightBracLimit - 1;
            
            _lefBracLimit = NO;
            _NumLimit = NO;
            _OperLimit = YES;
            
            _pointLimitByNum = NO;
            _pointLimitByOper = YES;
            _OperLimitJJ = YES;
        }
    }
}

小数点使用两个属性限制。一个属性限制小数点前存在数字，一个属性限制两个有效的小数点之间存在一个有效运算符，保证一个数字只有一个小数点。

MainViewController全部代码

MainViewController.h

#import <UIKit/UIKit.h>
#import "MainView.h"
#import "CalculatorModel.h"

NS_ASSUME_NONNULL_BEGIN

@interface MainViewController : UIViewController

@property (nonatomic, strong) MainView* mainView;

@property (nonatomic, strong) CalculatorModel* model;

@property (nonatomic, assign) NSInteger rightBracLimit;
@property (nonatomic, assign) BOOL lefBracLimit;
@property (nonatomic, assign) BOOL OperLimit;
@property (nonatomic, assign) BOOL NumLimit;
@property (nonatomic, assign) BOOL pointLimitByNum;
@property (nonatomic, assign) BOOL pointLimitByOper;
@property (nonatomic, assign) BOOL OperLimitJJ;

@end

NS_ASSUME_NONNULL_END

MainViewController.m

#import "MainViewController.h"

#define MAXSIZE 100

@interface MainViewController ()

@end

@implementation MainViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    [self createView];
    
    [self createModel];
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

- (void) createView {
    self.mainView = [[MainView alloc] initWithFrame:self.view.bounds];
    
    [self.mainView initView];
    
    [self.view addSubview:self.mainView];
    
    // 设置按钮初始限制状态
    _rightBracLimit = 0;
    _lefBracLimit = YES;
    _NumLimit = YES;
    _OperLimit = NO;
    _pointLimitByNum = NO;
    _pointLimitByOper = YES;
    _OperLimitJJ = YES;
    
    for (UIButton* button in self.mainView.buttonArray) {
        [button addTarget:self action:@selector(pressButton:) forControlEvents:UIControlEventTouchUpInside];
    }
    
    [self.mainView.ACButton addTarget:self action:@selector(pressAcButton:) forControlEvents:UIControlEventTouchUpInside];
    
    [self.mainView.equalButton addTarget:self action:@selector(pressEqualButton:) forControlEvents:UIControlEventTouchUpInside];
    
    [self.mainView.pointButton addTarget:self action:@selector(pressPiontButton:) forControlEvents:UIControlEventTouchUpInside];
}

- (void) pressButton:(UIButton*)sender {
    if (sender.tag / 100 == 1) {
        [self pressBracButton:sender];
    } else if (sender.tag / 100 == 2) {
        [self pressOperButton:sender];
    } else if (sender.tag / 100 == 3) {
        [self pressNumberButton:sender];
    }
}

// 处理括号
- (void) pressBracButton:(UIButton*)sender {
    if (sender.tag == 101) {
        if (_lefBracLimit) {
            NSString* oldCalculation = self.mainView.calculation.text;
            NSString* newChar = sender.titleLabel.text;
            NSString* newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
            
            self.mainView.calculation.text = newCalculation;
            
            if (_rightBracLimit < 0) {
                _rightBracLimit = -_rightBracLimit;
            }
            _rightBracLimit++;
            _OperLimit = NO;
            _NumLimit = YES;
            _OperLimitJJ = YES;
            
            _pointLimitByNum = NO;
            _pointLimitByOper = YES;
        }
    } else {
        if (_rightBracLimit > 0) {
            NSString* oldCalculation = self.mainView.calculation.text;
            NSString* newChar = sender.titleLabel.text;
            NSString* newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
            
            self.mainView.calculation.text = newCalculation;
            
            _rightBracLimit = _rightBracLimit - 1;
            
            _lefBracLimit = NO;
            _NumLimit = NO;
            _OperLimit = YES;
            
            _pointLimitByNum = NO;
            _pointLimitByOper = YES;
            _OperLimitJJ = YES;
        }
    }
}

- (void) pressOperButton:(UIButton*)sender {
    if (sender.tag > 201) {
        [self pressOperButtonCC:sender];
    } else {
        [self pressOperButtonJJ:sender];
    }
}

// C:乘 C:除
- (void) pressOperButtonCC:(UIButton*)sender {
    if (_OperLimit) {
        NSString* oldCalculation = self.mainView.calculation.text;
        NSString* newChar = sender.titleLabel.text;
        NSString* newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
        
        self.mainView.calculation.text = newCalculation;
        
        _OperLimit = NO;
        _OperLimitJJ = NO;
        _NumLimit = YES;
        _lefBracLimit = YES;
        if (_rightBracLimit > 0) {
            _rightBracLimit = -_rightBracLimit;
        }
        _pointLimitByOper = YES;
        _pointLimitByNum = NO;
    }
}

// J:加 J:减
- (void) pressOperButtonJJ:(UIButton*)sender {
    if (_OperLimitJJ) {
        NSString* oldCalculation = self.mainView.calculation.text;
        NSString* newChar = sender.titleLabel.text;
        NSString* newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
        
        self.mainView.calculation.text = newCalculation;
        
        _OperLimit = NO;
        _OperLimitJJ = NO;
        _NumLimit = YES;
        _lefBracLimit = YES;
        if (_rightBracLimit > 0) {
            _rightBracLimit = -_rightBracLimit;
        }
        _pointLimitByOper = YES;
        _pointLimitByNum = NO;
    }
}

- (void) pressNumberButton:(UIButton*)sender {
    if (self.NumLimit) {
        NSString* oldCalculation = self.mainView.calculation.text;
        NSString* newChar = sender.titleLabel.text;
        NSString* newCalculation = nil;
        if ([newChar isEqual:@"0          "]) {
            newCalculation = [NSString stringWithFormat:@"%@0", oldCalculation];
        } else {
            newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
        }
        
        self.mainView.calculation.text = newCalculation;
        
        _lefBracLimit = NO;
        if (_rightBracLimit < 0) {
            _rightBracLimit = -_rightBracLimit;
        }
        _OperLimit = YES;
        _OperLimitJJ = YES;
        if (_pointLimitByOper) {
            _pointLimitByNum = YES;
        }
    }
}

- (void) pressPiontButton:(UIButton*)sender {
    if (_pointLimitByNum &amp;&amp; _pointLimitByOper) {
        NSString* oldCalculation = self.mainView.calculation.text;
        NSString* newChar = sender.titleLabel.text;
        NSString* newCalculation = [NSString stringWithFormat:@"%@%@", oldCalculation, newChar];
        
        self.mainView.calculation.text = newCalculation;
        
        _OperLimit = NO;
        _NumLimit = YES;
        _lefBracLimit = NO;
        if (_rightBracLimit > 0) {
            _rightBracLimit = -_rightBracLimit;
        }
        _pointLimitByNum = NO;
        _pointLimitByOper = NO;
        _OperLimitJJ = NO;
    }
}

- (void) pressAcButton:(UIButton*)sender {
    self.mainView.calculation.text = nil;
    
    // 设置按钮初始限制状态
    _rightBracLimit = 0;
    _lefBracLimit = YES;
    _NumLimit = YES;
    _OperLimit = NO;
    _pointLimitByNum = NO;
    _pointLimitByOper = YES;
    _OperLimitJJ = YES;
}

- (void) pressEqualButton:(UIButton*)sender {
    
    NSString* oldCalculation = self.mainView.calculation.text;
    NSString* newChar = sender.titleLabel.text;
    NSMutableString* newCalculation = [NSMutableString stringWithFormat:@"%@%@", oldCalculation, newChar];
    
    for (int i = 0; i < oldCalculation.length; i++) {
        NSString* s = [oldCalculation substringWithRange:NSMakeRange(i, 1)];
        
        if ([s isEqualToString:@"÷"]) {
            [newCalculation replaceCharactersInRange:NSMakeRange(i, 1) withString:@"/"];
        } else if ([s isEqualToString:@"×"]) {
            [newCalculation replaceCharactersInRange:NSMakeRange(i, 1) withString:@"*"];
        }
    }
    
    if ([self isCalculationTrue:newCalculation]) {
        [self.model Calculat:newCalculation];
    } else {
        self.mainView.calculation.text = @"error";
    }
    
    // 设置按钮初始限制状态
    _rightBracLimit = 0;
    _lefBracLimit = NO;
    _NumLimit = YES;
    _OperLimit = YES;
    _pointLimitByNum = NO;
    _pointLimitByOper = YES;
    _OperLimitJJ = YES;
}

- (BOOL) isCalculationTrue:(NSString*)calculation {
    if ([calculation containsString:@"e"]) {
        return NO;
    } else if ([calculation containsString:@"r"]) {
        return NO;
    } else if ([calculation containsString:@"o"]) {
        return NO;
    } else if (_rightBracLimit) {
        return NO;
    } else {
        NSInteger index = calculation.length - 2;
        NSString* s = [calculation substringWithRange:NSMakeRange(index, 1)];
        
        if ([s isEqualToString:@"+"]) {
            return NO;
        } else if ([s isEqualToString:@"-"]) {
            return NO;
        } else if ([s isEqualToString:@"*"]) {
            return NO;
        } else if ([s isEqualToString:@"/"]) {
            return NO;
        } else {
            return YES;
        }
    }
}

- (void) createModel {
    self.model = [[CalculatorModel alloc] init];
    
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(upAnswer:) name:@"answer" object:nil];
    
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(upError) name:@"error" object:nil];
}

- (void) upAnswer:(NSNotification*)notification {
    NSDictionary* answer = notification.userInfo;
    
    
    self.mainView.calculation.text = answer[@"Value"];
}

- (void) upError {
    self.mainView.calculation.text = @"error";
}

@end

运算

首先我需要模拟一个栈。我是建立一个对象CalculatorStack。
CalculatorStack.h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

#define MAXSIZE 100

NS_ASSUME_NONNULL_BEGIN

@interface CalculatorStack : NSObject
{
    CGFloat _data[MAXSIZE];
    NSInteger _top;
}

- (void) Push:(CGFloat)element;
- (CGFloat) Pop;
- (CGFloat) GetTop;
- (void) initStack;

@end

NS_ASSUME_NONNULL_END

CalculatorStack.m

#import "CalculatorStack.h"

@implementation CalculatorStack
- (id) init {
    if (self = [super init]) {
        _top = -1;
    }
    return self;
}

- (void) initStack {
    _top = -1;
}

- (void) Push:(CGFloat)element {
    if (_top == 99) {
        return;
    }
    _data[++_top] = element;
}

- (CGFloat) Pop {
    if (_top == -1) {
        return 0;
    }
    return _data[_top--];
}

- (CGFloat) GetTop {
    if (_top == -1) {
        return 0;
    }
    return _data[_top];
}

@end

在Model中计算，我使用后缀表达式。

1. 建立两个栈，一个存数字，一个存运算符。
2. 向运算符栈压入一个“=”，主要用于计算第一个运算符的优先级。
3. 从左向右扫描表达式。
4. 遇到数字存入数字栈。
5. 遇到运算符，与栈顶运算符比较优先级。优先级大，压入栈中；优先级小，计算栈顶运算符；优先级相等，证明匹配到“()”，弹出栈顶运算符。

CalculatorModel.h

#import <Foundation/Foundation.h>
#import "CalculatorStack.h"

NS_ASSUME_NONNULL_BEGIN

@interface CalculatorModel : NSObject
{
    CalculatorStack* _Num;
    CalculatorStack* _Oper;
}
- (void) Calculat:(NSString*)calculationString;
@end

NS_ASSUME_NONNULL_END

CalculatorModel.m

#import "CalculatorModel.h"

int  cmp[7][7]  = {
        { 2, 2, 1, 1, 1, 2, 2 },
        { 2, 2, 1, 1, 1, 2, 2 },
        { 2, 2, 2, 2, 1, 2, 2 },
        { 2, 2, 2, 2, 1, 2, 2 },
        { 1, 1, 1, 1, 1, 3, 0 },
        { 2, 2, 2, 2, 0, 2, 2 },
        { 1, 1, 1, 1, 1, 0, 3 }  };

char op[7] = {'+', '-', '*', '/', '(', ')', '='};

@implementation CalculatorModel

- (id) init {
    if (self = [super init]) {
        _Num = [[CalculatorStack alloc] init];
        _Oper = [[CalculatorStack alloc] init];
    }
    return self;
}

- (BOOL) inCalculator:(char)ch {
    if (ch == '+' || ch == '*' || ch == '/' || ch == '-' || ch == '(' || ch == ')' || ch == '=') {
        return YES;
    }
    return NO;
}

- (char) CompareOper1:(char)oper1 AndOper2:(char)oper2 {
    int m = 0, n = 0, i, ans;
    for(i = 0; i < 7; i++) {
        if(oper1 == op[i]) {
            m = i;
        }
        if(oper2 == op[i]) {
            n = i;
        }
    }
    ans = cmp[m][n];
    switch (ans) {
        case 2:
            return (char)('<');
        case 1:
            return (char)('>');
        case 3:
            return (char)('=');
        default:
            return 0;
        }
}

- (CGFloat) countNum1:(CGFloat)num1 Num2:(CGFloat)num2 AndOper:(char)oper {
    CGFloat val = 0;
    switch (oper) {
        case '+':
            val = num1 + num2;
            break;
        case '-':
            val = num1 - num2;
            break;
        case '*':
            val = num1 * num2;
            break;;
        case '/':
            val = num1 / num2;
            break;
        default:
            break;
    }
    
    return val;
}

- (void) Calculat:(NSString *)calculationString {
    
    [_Oper initStack];
    [_Num initStack];
    
    char* calculation = (char*)[calculationString UTF8String];
    NSInteger length = calculationString.length;
    char ch;
    CGFloat x1, x2, val;
    char oper;
    int BracFlage = 0;
    int flage = 0;
    
    [_Oper Push:'='];
    
    for (int i = 0; i < length; i++) {
        ch = calculation[i];
        
        if (![self inCalculator:ch]) {
            val = 0;
            while (![self inCalculator:ch] &amp;&amp; i < length) {
                val = val * 10 + (ch - '0');
                ch = calculation[++i];
                if (ch == '.') {
                    ch = calculation[++i];
                    int j = 1;
                    while (![self inCalculator:ch] &amp;& i < length) {
                        CGFloat f = (CGFloat)(ch - '0');
                        val = val + f / (10 * j);
                        j++;
                        ch = calculation[++i];
                    }
                }
            }
            i--;
            if (flage== 0) {
                [_Num Push:val];
            } else {
                [_Num Push:-val];
                flage = 0;
            }
        } else {
            if (BracFlage == 0 || (ch != '-' && ch != '+')) {
                switch([self CompareOper1:[_Oper GetTop] AndOper2:ch]) {
                    case '>':
                        [_Oper Push:ch];
                        break;
                    case '=':
                        [_Oper Pop];
                        break;
                    case '<':
                        oper = [_Oper Pop];
                        x2 = [_Num Pop];
                        x1 = [_Num Pop];
                        if (oper == '/' && x2 == 0) {
                            [[NSNotificationCenter defaultCenter] postNotificationName:@"error" object:nil];
                            return;
                        }
                        val = [self countNum1:x1 Num2:x2 AndOper:oper];
                        [_Num Push:val];
                        i--;
                        break;
                    default:
                        break;
                }
            }
            if (BracFlage == 1 && ch == '-') {
                flage = 1;
            }
            if (BracFlage == 1 && ch == ')') {
                [[NSNotificationCenter defaultCenter] postNotificationName:@"error" object:nil];
                return;
            }
        }
        BracFlage = 0;
        if (ch == '(') {
            BracFlage = 1;
        }
    }
    [self CGFloatToNSString:[_Num Pop]];
}

- (void) CGFloatToNSString:(CGFloat)answer {
    NSMutableString* answerString = [NSMutableString stringWithFormat:@"%lf", answer];
    if (![answerString isEqualToString:@"0"]) {
        for (NSInteger i = answerString.length - 1; i >= 0; i--) {
            NSString* s = [answerString substringWithRange:NSMakeRange(i, 1)];
            if ([s isEqualToString:@"0"]) {
                [answerString deleteCharactersInRange:NSMakeRange(i, 1)];
            } else if ([s isEqualToString:@"."]) {
                [answerString deleteCharactersInRange:NSMakeRange(i, 1)];
                break;
            } else {
                break;;
            }
        }
    }
    
    NSDictionary* answerDict = [NSDictionary dictionaryWithObject:answerString forKey:@"Value"];
    
    [[NSNotificationCenter defaultCenter] postNotificationName:@"answer" object:nil userInfo:answerDict];
}

@end

注：我使用两个flag分辨正负号和加减号。我们需要将加减号当作正负号处理的情况只有一种，就是在左括号后紧跟的加减号。我们一个flag检测左括号，一个flag检测加减号。如果我们在检测到左括号后紧跟着检测到加减号，就见此次加减号当作正负号处理。

代码007普通

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