UIViewController viewDidLayoutSubviews

Question

彼女の料理本の例Ch07-11で、Erica Sadunが（viewDidLayoutSubviewsでviewDidAppearを呼び出す）理由を理解するのが難しいです。おそらく、2つのメソッドは代わりに別のメソッドを呼び出す必要がありますか？

参照：https://github.com/erica/iOS-5-Cookbook/tree/master/C07

- (void) viewDidAppear:(BOOL)animated 
{ 
    scrollView.frame = self.view.bounds; 
    scrollView.center = CGRectGetCenter(self.view.bounds); 

    if (imageView.image) 
    { 
     float scalex = scrollView.frame.size.width/imageView.image.size.width; 
     float scaley = scrollView.frame.size.height/imageView.image.size.height; 
     scrollView.zoomScale = MIN(scalex, scaley); 
     scrollView.minimumZoomScale = MIN(scalex, scaley); 
    } 
} 

- (void) viewDidLayoutSubviews 
{ 
    [self viewDidAppear:NO]; 
} 

任意のアイデアなぜですか？

Answer 1

これはちょうど私に間違っています。これらのメソッドが呼び出されたときにUIKitを処理させます。 viewDidLayoutSubviews内のレイアウトsrollViewがscrollViewが少し吃音を取得する必要がありますスクロール、あなたはup.ThenをsettedいたscrollViewが変わりますので

 
- (void)viewDidAppear:(BOOL)animated { 
    [super viewDidAppear:animated]; // Always call super with this!!! 

    [self doSomeCustomLayoutStuff]; // I don't actually think this is necessary. viewWillLayoutSubviews is meant for laying out subviews, and gets called automatically in iOS 5 and beyond. 

} 

- (void)viewWillLayoutSubviews { 
    [super viewWillLayoutSubviews]; 

    [self doSomeCustomLayoutStuff]; 
} 

- (void)doSomeCustomLayoutStuff { 
    scrollView.frame = self.view.bounds; 
    scrollView.center = CGRectGetCenter(self.view.bounds); 

    if (imageView.image) 
    { 
     float scalex = scrollView.frame.size.width/imageView.image.size.width; 
     float scaley = scrollView.frame.size.height/imageView.image.size.height; 
     scrollView.zoomScale = MIN(scalex, scaley); 
     scrollView.minimumZoomScale = MIN(scalex, scaley); 
    } 
} 

Answer 2

：

は、代わりにこれを行います。