這是正確的方式淡入淡出UIView嗎？

Question

這淡入並通過按下一個按鈕，褪色的UIView，但目前看來，這個代碼可以寫更好：

- (IBAction)navigationTap:(id)sender { 
if (navigationFolded == TRUE) { 
    [UIView beginAnimations:@"MoveOut" context:nil]; 
    [UIView setAnimationCurve:UIViewAnimationCurveEaseIn]; 
    [UIView setAnimationDuration:0.2f]; 
    self.moveMe.frame = CGRectMake(0, 0, _moveMe.bounds.size.width, _moveMe.bounds.size.height); 
    [UIView commitAnimations]; 
    navigationFolded = FALSE; 
} else { 
    [UIView beginAnimations:@"MoveIn" context:nil]; 
    [UIView setAnimationCurve:UIViewAnimationCurveEaseIn]; 
    [UIView setAnimationDuration:0.2f]; 
    self.moveMe.frame = CGRectMake(50-_moveMe.bounds.size.width, 0, _moveMe.bounds.size.width, _moveMe.bounds.size.height); 
    [UIView commitAnimations]; 
    navigationFolded = TRUE; 
} 

Answer 1

你可以使用：

- (IBAction)navigationTap:(id)sender { 
if (navigationFolded == TRUE) { 
    [UIView beginAnimations:@"MoveOut" context:nil]; 
    [UIView setAnimationCurve:UIViewAnimationCurveEaseIn]; 
    [UIView setAnimationDuration:0.2f]; 
    self.moveMe.alpha = 1; 
    [UIView commitAnimations]; 
    navigationFolded = FALSE; 
} else { 
    [UIView beginAnimations:@"MoveIn" context:nil]; 
    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut]; 
    [UIView setAnimationDuration:0.2f]; 
    self.moveMe.alpha = 0; 
    [UIView commitAnimations]; 
    navigationFolded = TRUE; 
} 

（也許是我的情況下混合起來 - 在這種情況下，IF語句應該使UIView可見，而其他的則會使它逐漸淡出YMMV）。

Answer 2

根據您的代碼，聽起來好像您希望UIView從屏幕的側面滑入。衰落將涉及動畫的UIView

你的代碼alpha值可以通過使用新的基於塊的語法做動畫，僅在if語句包裹的x位置的只是價值被簡化，因爲它是唯一的一部分更改爲navigationFolded。

- (IBAction)navigationTap:(id)sender { 
    NSInteger xPos = 0; 
    if (!navigationFolded) { 
     xPos = 50-_moveMe.bounds.size.width 
    } 

    [UIView animateWithDuration:0.2f delay:0 options:UIViewAnimationOptionCurveEaseIn animations:^{ 
     self.moveMe.frame = CGRectMake(xPos, 0, _moveMe.bounds.size.width, _moveMe.bounds.size.height); 
    } completion:nil]; 

    navigationFolded = !navigationFolded; 
}