无法更改NSArray对象的属性

Question

我有一个：

@property(nonatomic, retain) NSArray * buttonsArray;

...
...
@synthesize buttonsArray;

当视图加载时我将其初始化为：

buttonsArray = [[NSArray alloc] initWithObjects:
                             [UIButton buttonWithType:UIButtonTypeRoundedRect],
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect],
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect],
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect],
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect], 
                             [UIButton buttonWithType:UIButtonTypeRoundedRect],
                             nil];

//此代码将按钮数组中的按钮放在我视图中的图像顶部。我将这些图像放在一个名为imagesArrayV;

的数组中

int counter = 0;


    counter=0;
    for (UIButton *button in buttonsArray) {

        button = [buttonsArray objectAtIndex:counter];
        [button setTag:counter]; // *********
        button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
        [button addTarget:self action:@selector(test:) forControlEvents:UIControlEventTouchDown];
        [button setTitle:@"Hello" forState:UIControlStateNormal];

        UIImageView *tempImage = [imagesArrayV objectAtIndex:counter];
        CGRect tempRect = tempImage.frame;
        button.frame = tempRect;

        [self.ViewMainV addSubview:button];
        counter++;
    } 

这样做的目的是节省在xcode中创建所有按钮并创建连接的时间。

我发布了一张图片，以便您可以了解...

无论如何，单击按钮时执行的方法是：

-(void) test: (id) sender{


    UIButton*btn = (UIButton*)(sender);


    int tagnumber = [btn tag];

    NSLog(@"%i",tagnumber);

}

当我按下按钮时，当我在创建按钮时将其设置为其他内容（查找：// *********）时标签等于0，为什么呢？而且当我运行这个方法时：

-(void) someOtherMethod{
    int counter = 0;
    for (UIButton *button in buttonsArray) {
        button = [buttonsArray objectAtIndex:counter];
        button.alpha = 0;
        button.titleLabel.text = @"I change the title";
        counter++;
    }
}

我之前添加的按钮根本没有变化。 alpha也不会改变。当我运行最后一个方法时，我不知道我正在改变什么按钮。

Answer 1

在您设置代码的行下方，您有一行button = [UIButton buttonWithType:UIButtonTypeRoundedRect];。这显然会覆盖按钮。然后将操作添加到新创建的按钮中，阵列中的按钮保持不变。

就个人而言，我会按如下方式重写代码：

for (int counter = 0; counter < numberOfButtons; ++counter) {
    button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [button setTag:counter];
    [button addTarget:self action:@selector(test:) forControlEvents:UIControlEventTouchDown];
    [button setTitle:@"Hello" forState:UIControlStateNormal];

    UIImageView *tempImage = [imagesArrayV objectAtIndex:counter];
    CGRect tempRect = tempImage.frame;
    button.frame = tempRect;

    [self.ViewMainV addSubview:button];
    [buttonsArray addObject:button];
} 

这也避免了对数组进行硬编码填充，以获得更灵活，更不容易出错的代码。

Answer 2

尝试使用此代码而不是上面的第三部分：

for(int i=0;i<[buttonsArray count];i++){
    UIButton *button=[buttonsArray objectAtIndex:i];
    [button addTarget:self action:@selector(test:) forControlEvents:UIControlEventTouchDown];
    [button setTitle:@"Hello" forState:UIControlStateNormal];

    UIImageView *tempImage  = [imagesArrayV objectAtIndex:counter];
    button.frame            = tempImage.frame;
    button.tag              =i;
    [self.ViewMainV addSubview:button];
}

其中一个问题是，您是在按钮上设置标记，然后替换下一行的按钮实例。

Answer 3

这看起来很可疑，你做了两次：

for (UIButton *button in buttonsArray) {

    button = [buttonsArray objectAtIndex:counter];

您不应该修改循环内的循环枚举变量按钮。你只需按原样使用按钮即可。

IOW，你要么：

for (counter = 0; counter < buttonsArray.count; counter++) 
{
    UIButton *button = [buttonsArray objectAtIndex: counter];
    button.alpha = 0;
    // etc...

或者您只是摆脱counter并执行：

for (UIButton * button in buttonsArray) 
{
    button.alpha = 0;
    // etc...