一次一个 UIButton

Question

这是我一直在玩的一些代码；由于某种原因，我无法让它一次创建一个按钮。例如你有； for(i = 1; i

//这里我们把按钮放在屏幕Y轴上的位置 浮动 startPositionY = 70.0;

for(int i = 1; i <= 4; i++) {

    NSString *button = [NSString stringWithFormat:@"button%i", i];

        // NSMutableString version to keep button from changing name.
        //NSString *button = [NSMutableString stringWithFormat:@"button%i", i];

    UIButton *tempBName = (UIButton *)[UIButton buttonWithType:UIButtonTypeRoundedRect];
    [tempBName setTitle:button forState:UIControlStateNormal];
    tempBName.tag = i;
    [tempBName addTarget:self action:@selector(clickMe:)forControlEvents:UIControlEventTouchUpInside];
    tempBName.frame = CGRectMake(0.0, 0.0, 80.0, 50.0);
    tempBName.center = CGPointMake(160.0, 50.0+startPositionY);
    tempBName.titleLabel.adjustsFontSizeToFitWidth = TRUE;
    [self.view addSubview:tempBName];

        // Make space between each button
    startPositionY += 70;

        // How many buttons out of "i" are we creating?
    NSLog(@"%d", i);

        // release button
    [button release];
}
    // Was the button Pressed?
NSLog(@"Did Press");
    // Did our Position change on the Y-axis?
NSLog(@"%f", startPositionY);

谢谢，

Answer 1

为什么不直接删除for 循环？如果您只想要一个按钮而不是四个按钮，则没有理由将代码运行四次...

Answer 2

您过度释放每个按钮，导致它从视图中消失。当您使用 [UIButton buttonWithType...] 创建按钮时，它会添加到自动释放池中，并且您没有它的所有权。当您将它添加到视图中时，它的保留计数会增加 1，从而为您提供所有权，但随后您使用 [按钮释放] 再次释放它。删除 [button release] 线，一切都应该很好。

我强烈建议您阅读 Apple 的内存管理编程指南。

我已经重写了您的代码，将按钮创建移到了每次单击添加按钮时都应调用的方法中。您还需要在头文件 (.h) 中声明一个名为 buttonCount 的 NSInteger 变量。

- (void)addButton {

        if (buttonCount == 4) return;
        buttonCount += 1;

        UIButton *tempBName = [UIButton buttonWithType:UIButtonTypeRoundedRect];
        [tempBName setTitle:[NSString stringWithFormat:@"button%i", buttonCount]; forState:UIControlStateNormal];
        tempBName.tag = buttonCount;
        [tempBName addTarget:self action:@selector(clickMe:)forControlEvents:UIControlEventTouchUpInside];
        tempBName.frame = CGRectMake(0.0, 50.0+(startPositionY*buttonCount)), 80.0, 50.0);
        // Removed the line setting the center, and move the positioning to the frame above
        tempBName.titleLabel.adjustsFontSizeToFitWidth = TRUE;
        [self.view addSubview:tempBName];
   }

Answer 3

嗯，这很好，我觉得很愚蠢。我昨天差点把它丢了。所以在这里回顾一下，这里是每个人的最终完整代码：

这段代码有什么作用？它允许在每次点击的基础上创建一个按钮。

[h 文件]：

@interface testMButton1ViewController : UIViewController {
    UIButton *addButton;
}
@property (nonatomic, retain) IBOutlet UIButton *addButton;
@property NSInteger buttonCount;
- (IBAction)addButton:(id)sender;

[m 文件]：

@synthesize addButton;
@synthesize buttonCount;

(IBAction)addButton:(id)sender {

    float startPositionY = 60.0;

    if (buttonCount == 6) return;
    buttonCount += 1;

    UIButton *tempBName = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [tempBName setTitle:[NSString stringWithFormat:@"button%i", buttonCount] forState:UIControlStateNormal];
    tempBName.tag = buttonCount;
    [tempBName addTarget:self action:@selector(clickMe:)forControlEvents:UIControlEventTouchUpInside];
    tempBName.frame = CGRectMake(0.0, 20.0+(startPositionY*buttonCount), 80.0, 50.0);
    tempBName.center = CGPointMake(160.0, 20.0+(startPositionY*buttonCount));
        // Removed the line setting the center, and move the positioning to the frame above
    tempBName.titleLabel.adjustsFontSizeToFitWidth = TRUE;
    [self.view addSubview:tempBName];
    NSLog(@"%d", buttonCount);
}

特别感谢 Run Loop 为完成这项工作所做的所有辛勤工作。