uiviewcontroller解除分配时如何在目标c中触发阻止事件 [英] how to fire block event in objective c when uiviewcontroller dealloc

问题描述

如何在UIViewController取消分配时在目标C中触发阻止事件.

How to fire block event in Objective C when UIViewController dealloc.

例如:

   [PGMemberObj requestWithUserName:@"ab" andPassword:@"cc" andCallback:^(BOOL isSuc){
        if (isSuc) {
            NSLog("Login Suc.");
        }else
        {
            NSLog("Login Failed");
        }
    }];

当我弹出ViewController并执行dealloc时，我仍然收到Login Suc.或登录失败消息. 如何避免这个问题?

when i pop ViewController and dealloc was executed,i still receive Login Suc. or Login Failed Message. How to avoid this issue?

推荐答案

尝试以下代码:

__weak UIViewController *weakSelf = self;
[PGMemberObj requestWithUserName:@"ab" andPassword:@"cc" andCallback:^(BOOL isSuc){
    if ([weakSelf isViewLoaded] && [weakSelf.view window]) 
        //The view controller still exists AND it's being shown on screen
    else
        //Either dealloc'd or not on screen anymore
 }];

它将测试您的视图控制器是否仍然存在并且仍在屏幕上. 只需检查weakSelf，如果您不在乎它是否仍在屏幕上显示.

It will test whether your view controller still exists AND is still on screen. Just check for weakSelf if you don't care if it's still being shown on screen.

if (weakSelf)
    //Still exists
else
    //dealloc'd

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