自定义类中的 UIButton 目标操作 [英] UIButton target action inside custom class

问题描述

我一直在努力解决一个错误，我找到了一个解决方法，但我想了解到底发生了什么.它与 UIButton 目标操作在子类内根据不同的子视图层次结构失火有关.

I've been struggling with a bug, and I found a work-around, but I'd like to understand what is exactly going on. it has something to do with UIButton target actions misfiring depending on different subview hierarchies, inside a subclass.

简要总结:我有一个 NSObject 的子类，它带有一个 UIView 属性对象、一个附加到它的 UIButton 和一个添加到按钮的目标，调用子类中的一个函数.在主 ViewController 中，我初始化了子类并将其视图添加到视图堆栈中，单击按钮，它会将我抛出到 main.mm 并显示错误 - EXC_BAD_ACCESS，给我的反馈很少.所以层次结构看起来像这样:

Brief summary: I have a subclass of NSObject with a UIView property object, a UIButton attached to it, and a target added to the button calling a function inside the subclass. Inside the main ViewController, I init the subclass and add its view to the view stack, click the button, and it throws me to main.mm with the error - EXC_BAD_ACCESS, gives me little feedback. so the hierarchy looks like this:

-CustomClass
--UIView           <-this is added as a subview to the View Controller
---UIButton (onRelease calling a function)

所以我通过将自定义类更改为UIView的子类而不是NSObject来修复它，然后将其@property UIView添加为自定义类的子视图(并且按钮仍然附加到子视图)，然后在主视图控制器中，我将自定义类本身添加为子视图，而不是类的子视图属性对象.然后按钮成功调用该函数.所以新的安排是这样的:

so I fixed it by changing the custom class to be a subclass of UIView instead of NSObject, then add its @property UIView to be a subview of the custom class (and the button is still attached to the subview), and then in the main View Controller, I add the custom class itself as a subview, not the class's subview property object. then the button successfully calls the function. so the new arrangement looks like this:

-CustomClass (now UIView)     <-this is added as a subview to the View Controller
--UIView                      <-this is added as a subview to CustomClass
---UIButton (onRelease calling a function)

然后，我意识到我可以将 CustomClass 保留为两个实例的 UIView 的子类，如果其他一切都没有改变，原始设置的问题仍然存在.

then, i realized i can just keep the CustomClass a subclass of UIView for both instances, the problem persists with the original setup if everything else is unchanged.

好的，更多细节，这里是代码:

okay, more detail, here's code:

自定义类:.h

@interface Temp : UIView
@property UIView *subview;
@property UIButton *but;
@end

.m

-(id) init{
    self = [super initWithFrame:[[UIScreen mainScreen] bounds]];
    if(self){
        _subview = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        //[self addSubview:_subview];  // FOR THE FIX
        _but = [UIButton buttonWithType:UIButtonTypeRoundedRect];
        [_but setTitle:@"OKAY" forState:UIControlStateNormal];
        [_but setBackgroundColor:[UIColor blackColor]];
        [_but setFrame:CGRectMake(50, 50, 200, 200)];
        [_subview addSubview:_but];
        [_but addTarget:self action:@selector(pageTurn) forControlEvents:UIControlEventTouchUpInside];
    }
    return self;
}

-(void) pageTurn{
    NSLog(@"WORKS");
}

内部视图控制器:

Temp *temp = [[Temp alloc] init];
[self.view addSubview:temp.subview];
//[self.view addSubview:temp];  // FOR THE FIX, instead of above line

推荐答案

谁在控制 temp?

如果 temp 没有被任何人引用，那么它就会被释放.那时目标是僵尸，当然你会崩溃.temp.subview 由 self.view 持有.

If temp isn't referenced by anyone then it's released. At that point the target is zombie and of course you will crash. temp.subview is being held by self.view.

在第二个设置中，添加 temp 作为 self.view 的子视图，保持对它的引用.

In the second setup, adding temp as a subview of self.view keeps a reference to it.

您可以通过在视图控制器中添加 Temp * 属性来解决此问题.

You can fix this by adding a Temp * property in the view controller.

self.temp = [[Temp alloc] init];
[self.view addSubview:self.temp.subview];

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