iOS01 计算器

        
          
        #import "ViewController.h"  
          
        @interface ViewController ()  
        {  
            UILabel *_display;  
            NSString *_operator1;  
            NSString *_operator;  
            NSString *_operator2;  
        }  
        @end  
          
        @implementation ViewController  
          
        - (void)viewDidLoad  
        {  
            [super viewDidLoad];  
            // Do any additional setup after loading the view, typically from a nib.  
            //创建UI界面  
            _display = [[UILabel alloc] initWithFrame:CGRectMake(10, 50, self.view.frame.size.width-20, 100)];  
            _display.backgroundColor = [UIColor grayColor];  
            _display.alpha = 0.8;  
            _display.textAlignment = NSTextAlignmentRight;  
            _display.numberOfLines = 2;  
            _display.text = @"";  
            _operator = @"";  
            _operator1 = @"";  
            _operator2 = @"";  
            [self.view addSubview:_display ];  
            NSArray *titleArray1 = @[@"MC",@"M+",@"M-",@"MR",@"清除"];  
            NSArray *titleArray2 = @[@[@"7",@"8",@"9",@"+"],@[@"4",@"5",@"6",@"-"],@[@"1",@"2",@"3",@"*"],@[@"0",@".",@"=",@"/"]];  
            CGFloat size1 = (self.view.frame.size.width-60)/5;  
            CGFloat size2 = (self.view.frame.size.width-50)/4;  
            for (int i=0; i<5; i++)  
            {  
                CGRect frame = CGRectMake(10+i*(size1+10), 180, size1, 50);  
                [self createButtonByFrame:frame withTitle:titleArray1[i]];  
            }  
            for (int i=0; i<4; i++)  
            {  
                for (int j=0; j<4; j++)  
                {  
                    [self createButtonByFrame:CGRectMake(10+j*(size2+10), 240+i*60, size2, 50) withTitle:titleArray2[i][j]];  
                }  
            }  
        }  
          
        - (void)createButtonByFrame:(CGRect)frame withTitle:(NSString *)title  
        {  
            UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];  
            btn.frame = frame;  
            btn.backgroundColor = [UIColor grayColor];  
            btn.alpha = 0.8;  
            btn.layer.cornerRadius = 10;  
            [btn setTitle:title forState:UIControlStateNormal];  
            btn.titleLabel.font = [UIFont systemFontOfSize:25];  
            [btn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];  
            [btn addTarget:self action:@selector(btnClicked:) forControlEvents:UIControlEventTouchUpInside];  
              
            [self.view addSubview:btn];  
        }  
          
        - (void)btnClicked:(UIButton *)btn  
        {  
            NSString *title = btn.currentTitle;  
            if ([title hasPrefix:@"M"])  
            {  
                  
            }  
            if ([title isEqualToString:@"清除"])  
            {  
                _display.text = @"";  
                _operator = @"";  
                _operator1 = @"";  
                _operator2 = @"";  
                return;  
            }  
            if ([self isOperator:title])  
            {  
                if (_operator.length)//判断操作运算符是否已经存在  
                {  
                    float result = 0.0;  
                    float value1 = [_operator1 floatValue];  
                    float value2 = [_operator2 floatValue];  
                    unichar ch = [_operator characterAtIndex:0];  
                    switch (ch)  
                    {  
                        case '+':  
                            result = value1+value2;  
                            break;  
                        case '-':  
                            result = value1-value2;  
                            break;  
                        case '*':  
                            result = value1*value2;  
                            break;  
                        case '/':  
                            result = value1/value2;  
                            break;  
                        default:  
                            break;  
                    }  
                    _operator1 = [NSString stringWithFormat:@"%g",result];  
                    _display.text = [NSString stringWithFormat:@"%@
%@",_operator1,title];  
                    _operator2 = @"";  
                    if ([btn.currentTitle isEqualToString:@"="])  
                    {  
                        _operator = @"";  
                    }  
                    else  
                    {  
                        _operator = title;  
                    }  
                }  
                else  
                {  
                    _operator = title;  
                    _display.text = [NSString stringWithFormat:@"%@
%@",_operator1,_operator];  
                }  
            }  
            else//是操作数  
            {  
                if (_operator.length)//判断是哪个操作数  
                {  
                    if ([_operator2 containsString:@"."] && [title isEqualToString:@"."])  
                    {  
                          
                    }  
                    else  
                    {  
                        _operator2 = [_operator2 stringByAppendingString:title];  
                        _display.text = [NSString stringWithFormat:@"%@
%@%@",_operator1,_operator,_operator2];  
                    }  
                }  
                else  
                {  
                    if ([_operator1 containsString:@"."] && [title isEqualToString:@"."])  
                    {  
                          
                    }  
                    else  
                    {  
                        _operator1 = [_operator1 stringByAppendingString:title];  
                        _display.text = _operator1;  
                    }  
                }  
            }  
        }  
          
        //判断标题是否为运算符+ - * / =  
        - (BOOL)isOperator:(NSString *)title  
        {  
            if ([[NSCharacterSet characterSetWithCharactersInString:@"+-*/="] characterIsMember:[title characterAtIndex:0]])  
            {  
                return YES;  
            }  
              
            return NO;  
        }  
        - (void)didReceiveMemoryWarning {  
            [super didReceiveMemoryWarning];  
            // Dispose of any resources that can be recreated.  
        }  
        @end