奇怪的视图行为

Question

我的应用程序中有一个函数，当键盘显示时，视图向上移动。不幸的是有一个错误;您第一次加载视图一切工作正常，但如果您切换到另一个视图，然后切换回来，视图不再移动:(

我添加了一些NSLog语句到我的代码来尝试和追踪问题。我正在使用NSNotification，而且工作正常，因为每次都调用方法。

然后我想也许这是一个视图坐标问题，所以我添加了打印出视图原点的语句。他们打印出正确的来源（'移动'的起源），尽管视图肯定没有移动。

因此，看起来Xcode认为它已经移动了视图，但它没有。有其他人遇到过这种行为吗？

---

编辑：这里是一些代码

设置的通知：

 //register for keyboard notifications 
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:self.view.window]; 

     //if the keyboard is already being shown because someone was entering a comment, and then they switch to a textfield, this will move the view back down. 
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UITextFieldTextDidBeginEditingNotification object:self.view.window]; 

     //hide the keyboard 
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:self.view.window]; 

     //hide the keyboard if we're done with the textview 
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UITextViewTextDidEndEditingNotification object:self.view.window]; 

     keyboardIsShown = FALSE; 

     tempDelegate.keyboardIsInitialized = TRUE; 

的方法来显示键盘和移动视图：

-(void)keyboardWillShow:(NSNotification *)notif{ 

    NSLog(@"keyboardWillShow"); 
    NSLog(@"type: %@, keyboardIsShown: %@", sender, keyboardIsShown); 

    //double check 
    if (keyboardIsShown || !sender) { 
     NSLog(@"return"); 
     return; 
    } 

    //only adjust screen for comment box (which is a textview) 
    if(![sender isEqualToString:@"text field"] && [sender isEqualToString:@"text view"]){ 

     NSLog(@"if"); 

     NSDictionary* userInfo = [notif userInfo]; 

     // get the size of the keyboard 
     CGSize keyboardSize = [[userInfo objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size; 

     [UIView beginAnimations:@"ResizeForKeyboard" context:NULL]; 
     [UIView setAnimationBeginsFromCurrentState:YES]; 
     [UIView setAnimationDuration:0.3]; 

     NSLog(@"regular BEFORE: %@", NSStringFromCGRect(regularView.frame)); 

     regularView.frame = CGRectMake(0, - keyboardSize.height, CGRectGetWidth(imageView.bounds)*scrollView.zoomScale, CGRectGetHeight(imageView.bounds)*scrollView.zoomScale); 

     NSLog(@"regular AFTER: %@", NSStringFromCGRect(regularView.frame)); 

     [UIView commitAnimations]; 

     keyboardIsShown = YES; 


    } 
} 

和方法隐藏键盘并将视图移回：

-(void)keyboardWillHide:(NSNotification *)notif{ 

    NSLog(@"keyboardWillHide"); 

    if (!keyboardIsShown) { 
     NSLog(@"return"); 
     return; 
    } 

    [UIView beginAnimations:@"ResizeForKeyboard" context:NULL]; 
    [UIView setAnimationBeginsFromCurrentState:YES]; 
    [UIView setAnimationDuration:0.3]; 

    NSLog(@"regular BEFORE: %@", NSStringFromCGRect(regularView.frame)); 


    self.regularView.frame = CGRectMake(0, 0, CGRectGetWidth(imageView.bounds)*scrollView.zoomScale, CGRectGetHeight(self.imageView.bounds)*scrollView.zoomScale); 
    [UIView commitAnimations]; 

    NSLog(@"regular AFTER: %@", NSStringFromCGRect(regularView.frame)); 



    keyboardIsShown = NO; 
} 

Answer 1

您是否在任何时候添加或删除NSNotification？

另外，你可以发布你的代码如何移动你的观点？那里可能有一些问题。

编辑：

因此，从什么，似乎是正在在某些时候删除您的通知，并没有被加回。

移动通知INIT到您的viewDidAppear方法，在你viewDidDissappear方法删除它们。这将确保您的视图出现或消失时分别添加或删除通知。

什么你可能做在你的viewDidLoad，其视图时首先加载（所以只有一次）这种方法只被调用时添加。所以，如果你推新视图然后弹出，它们可能会被删除，而不是加回来。

编辑：

这里是代码卡盘时，我需要用键盘进行动画，我通常使用。

#define kOFFSET_FOR_KEYBOARD 80.0 

-(void)keyboardWillShow { 
    // Animate the current view out of the way 
    if (self.view.frame.origin.y >= 0) 
    { 
     [self setViewMovedUp:YES]; 
    } 
    else if (self.view.frame.origin.y < 0) 
    { 
     [self setViewMovedUp:NO]; 
    } 
} 

-(void)keyboardWillHide { 
    if (self.view.frame.origin.y >= 0) 
    { 
     [self setViewMovedUp:YES]; 
    } 
    else if (self.view.frame.origin.y < 0) 
    { 
     [self setViewMovedUp:NO]; 
    } 
} 

-(void)textFieldDidBeginEditing:(UITextField *)sender 
{ 
    if ([sender isEqual:mailTf]) 
    { 
     //move the main view, so that the keyboard does not hide it. 
     if (self.view.frame.origin.y >= 0) 
     { 
      [self setViewMovedUp:YES]; 
     } 
    } 
} 

//method to move the view up/down whenever the keyboard is shown/dismissed 
-(void)setViewMovedUp:(BOOL)movedUp 
{ 
    [UIView beginAnimations:nil context:NULL]; 
    [UIView setAnimationDuration:0.3]; // if you want to slide up the view 

    CGRect rect = self.view.frame; 
    if (movedUp) 
    { 
     // 1. move the view's origin up so that the text field that will be hidden come above the keyboard 
     // 2. increase the size of the view so that the area behind the keyboard is covered up. 
     rect.origin.y -= kOFFSET_FOR_KEYBOARD; 
     rect.size.height += kOFFSET_FOR_KEYBOARD; 
    } 
    else 
    { 
     // revert back to the normal state. 
     rect.origin.y += kOFFSET_FOR_KEYBOARD; 
     rect.size.height -= kOFFSET_FOR_KEYBOARD; 
    } 
    self.view.frame = rect; 

    [UIView commitAnimations]; 
} 


- (void)viewWillAppear:(BOOL)animated 
{ 
    // register for keyboard notifications 
    [[NSNotificationCenter defaultCenter] addObserver:self 
             selector:@selector(keyboardWillShow) 
              name:UIKeyboardWillShowNotification 
              object:nil]; 

    [[NSNotificationCenter defaultCenter] addObserver:self 
             selector:@selector(keyboardWillHide) 
              name:UIKeyboardWillHideNotification 
              object:nil]; 
} 

- (void)viewWillDisappear:(BOOL)animated 
{ 
    // unregister for keyboard notifications while not visible. 
    [[NSNotificationCenter defaultCenter] removeObserver:self 
              name:UIKeyboardWillShowNotification 
              object:nil]; 

    [[NSNotificationCenter defaultCenter] removeObserver:self 
              name:UIKeyboardWillHideNotification 
              object:nil]; 
} 

Answer 2

你使用：

-(void) viewWillDisappear:(BOOL)animated { 
    NSLog (@"Unregister for keyboard events"); 
    [[NSNotificationCenter defaultCenter] 
       removeObserver:self]; 
} 

如果这不是它尝试做对viewWillAppear中的观点..的位置的检查，如果它显示的键盘了..驳回W/O使用动画。

Answer 3

您是初始化regularViewviewWillAppear:还是viewDidAppear:？如果是这样，您应该将初始化移至viewDidLoad。

当你确认它是，该解释是viewWillAppear:可以被称为一种观点的一生很多次，所以它通常是不恰当的构建UI层次结构中viewWillAppear:因为你最终会与重复的视图层次。