在Objective-C

Question

提取從self.window視圖在我：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions: 

我設置以下scrollView：

UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:screenRect]; 
[self.window addSubview:scrollView]; 

在以後的方法，我怎麼會那麼毀了這個觀點，也就是從self.window中刪除它。

Answer 1

通常我不會在application:didFinishLaunchingWithOptions:中添加scrollView。相反，請在視圖控制器中創建UIScrollView，或者在viewDidLoad方法中或在故事板中創建UIScrollView。

無論哪種方式，刪除scrollView將看起來像這樣。首先創建一個屬性來存儲參考UIScrollView：

@property (nonatomic, weak) UIScrollView *scrollView; // Use a weak reference to the scrollview, that way once its removed from the superview (which keeps a strong reference to its subviews), the scrollview will be deallocated. 

然後初始化屬性，並將其添加爲子視圖：

self.scrollView = [[UIScrollView alloc] initWithFrame:screenRect]; 
[self.window addSubview:scrollView]; 

之後，你可以將其刪除：

[self.scrollView removeFromSuperview];