NSNotificationCenter调用两次 [英] NSNotificationCenter calling two times

问题描述

下面是我所拥有的.

- (IBAction)sideMenuAction:(id)sender {
    NSLog(@"login==sideMenuAction");
    [[NSNotificationCenter defaultCenter] postNotificationName:@"ShowMySideMenuNotification" object:self];
}

NotificationListener.m

-(void)viewDidLoad {
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"ShowMySideMenuNotification" object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(adjustShowMenu) name:@"ShowMySideMenuNotification" object:nil];
}

-(void) adjustShowMenu {
    NSLog(@"notification adjustShowMenu=");
}

现在，当我在MainViewController中单击侧边菜单按钮时，我期望的是从NotificationListener调用一次AdjustShowMenu，但是它被调用了两次.

Now when I click side menu button in MainViewController, what I was expecting is call adjustShowMenu from NotificationListener once, however it is called twice.

下面是相同的NSLog.

Below is the NSLog for the same.

2015-01-20 12:27:30.798 abc[699:169314] login==sideMenuAction
2015-01-20 12:27:30.798 abc[699:169314] notification adjustShowMenu=
2015-01-20 12:27:30.799 abc[699:169314] notification adjustShowMenu=

我期望的是

2015-01-20 12:27:30.798 abc[699:169314] login==sideMenuAction
2015-01-20 12:27:30.798 abc[699:169314] notification adjustShowMenu=

有什么想法吗?

注意:我也尝试在viewDidAppear中而不是viewDidLoad中进行尝试，但结果相同.

Note: I also tried in viewDidAppear instead of viewDidLoad, but its giving same result.

当我在线搜索时，有很多答案要求删除Observer.我做了同样的事情，但是仍然有两次通知被调用.

When I searched online, many answers asked to removeObserver. I did same, but still twice notification is getting called.

推荐答案

根据在此处回答，下方，并且现在可以正常工作.

As per answer here, I make changes as below and its working fine now.

-(void) viewWillAppear:(BOOL)animated {
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(adjustShowMenu) name:@"ShowMySideMenuNotification" object:nil];
}

-(void) viewWillDisappear:(BOOL)animated {
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"ShowMySideMenuNotification" object:nil];
}

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