Storyboard segues 导致内存泄漏 [英] Storyboard segues causing memory leaks

问题描述

我有两个 UIViewControllers，它们的按钮可以相互触发 segue(模态).我想知道在来回跳跃时是否会导致任何内存泄漏，我看到了 Living Object &&分配的内存正在增加，最终会导致应用程序崩溃.我没有任何一行代码 - 使用纯 UIViewControllers.

I have two UIViewControllers with buttons triggering segue (modal) to each other. I wanted to discover if that's causing any memory leaks while jumping back and forth and I see that Living Object && allocated memory is going up, what eventually would leave to app crash. I don't have any single line of code - working with pure UIViewControllers.

我可能做错了什么?
我可能在项目设置中设置错误吗?
我是否在阅读分析器的静态学很差?
在使用 segue 时是否需要执行任何特殊的发布命令?

What I might be doing wrong?
Could have I set something wrong in project settings?
Am I reading profiler's statictics badly?
Do I need to make any special release commands while working with segues?

推荐答案

您没有正确使用模态转场.您实现它的方式是，当您转场而不是返回到您来自的实例时，您正在为每个视图控制器创建一个新实例.这就是您的内存使用量不断增加的原因.

You aren't using the modal segues correctly. The way you have implemented it, you are creating a new instance of each view controller when you segue instead of returning to the instance you came from. That is why your memory usage continues to increase.

在 iOS 6 之前，正确的处理方法是:

Before iOS 6, the correct way to handle this was to:

1) 在视图控制器 1
中定义一个方法，例如 viewController2Done2) 在视图控制器 2 中，创建一个名为 delegate 的属性，其类型为 id.
3) 在视图控制器 1 的 prepareToSegue 中，将视图控制器 2 中的 delegate 设置为 self
4) 在视图控制器 2 中，当需要返回视图控制器 1 时，调用 [delegate viewController2Done]
5) 在 viewController2Done 调用 [self deniedModalViewControllerAnimated:YES]

1) define a method such as viewController2Done in view controller 1
2) in view controller 2, create a property called delegate of type id.
3) in prepareToSegue for view controller 1, set delegate in view controller 2 to self
4) in view controller 2, when it is time to return to view controller 1, call [delegate viewController2Done]
5) in viewController2Done call [self dismissModalViewControllerAnimated:YES]

此方法在 iOS 6 中仍然有效，但也可以使用新的 unwind segue 代替.要使用它，您需要在视图控制器 1 中定义一个方法，如下所示:

This method still works in iOS 6, but there is also a new unwind segue that can be used instead. To use it, you would define a method in your view controller 1 like so:

目标 C:

- (IBAction)unwindFromViewController2:(UIStoryboardSegue *)segue
{
    NSLog(@"and we are back");
}

斯威夫特:

@IBAction func unwindFromViewController2(_ segue: UIStoryboardSegue) {
    print("and we are back")
}

然后，您将控制从视图控制器 2 中的按钮拖动到故事板中视图控制器上方栏中的橙色退出图标.在弹出窗口中，您将选择 unwindFromViewController2 并且瞧，您大功告成了.

Then you'd control drag from the button in view controller 2 to the orange exit icon in the bar above the view controller in the Storyboard. In the pop up, you'd select unwindFromViewController2 and voila, you're done.

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