哪裏編碼子視圖的位置和配置屬於一個UIViewController的UIView

Question

我只是想到，我可能沒有這樣做的權利。我曾多次被告知，viewDidLoad方法在第一次參考self.view時被調用。因此，以下代碼

- (id)initWithFrame:(CGRect)frame{ 
self = [super initWithNibName:nil bundle:nil]; 
if (self) { 

    self.view.frame = frame; 

    } 
    return self; 
} 

在執行viewDidLoad之後完成了幀分配。

因此，任何在viewDidLoad之內對self.view.frame的引用都不會引用正確的幀。更重要的是，如果我在主視圖（self.view）內的子視圖中使用autoresizingMask（struts和spring），則任何比例間距都將基於錯誤的初始比例。關於autoresizingMask的文檔狀態如下：

當沿同一軸設置了多個選項時，默認行爲是在可變部分之間按比例分配大小差異。

什麼是正確的方式來配置UIViewController的視圖？是否像在viewWillAppear或viewDidAppear方法中配置和添加子視圖一樣簡單？

Answer 1

當您將其view設置爲UIViewController時，如果該視圖尚未實例化（這是您第一次提出要求），則需要創建它（°）。

當一個視圖控制器需要實例其觀點：如果一個XIB與您UIViewController相關

• ，則畫面從XIB加載。這意味着XIB文件是非存檔的，並且XIB中描述的所有對象都被分配/實例化。 XIB中的每個視圖因此通過使用alloc + initWithCoder: + autorelease（NSCoder是解壓縮XIB的解碼器）來實例化。因此，您的每個意見都會收到initWithCoder:消息
• 如果沒有你UIViewController有關廈門國際銀行，它會調用其loadView方法，讓您以編程方式創建視圖。在這種情況下，你在那裏編寫代碼來創建你的視圖，如[[[UIView alloc] initWithFrame:...] autorelease]。因此，您的視圖將通過代碼實例化並接收initWithFrame:消息，而不是initWithCoder:方法。
• 其中UIViewController視圖已經或者通過取消歸檔XIB文件或通過在loadView代碼創建和實例化，所述視圖被加載和UIViewController接收viewDidLoad消息。

所以每個視圖收到任一initWithFrame:或initWithCoder:（如果來自XIB創建）消息（如果由代碼創建）第一，然後一旦UIViewController的view創建的所有視圖的層次結構，所述UIViewController本身收到viewDidLoad消息。這總是按照這個順序。

---

@implementation YourCustonUIView 
- (id)initWithCoder:(NSCoder*)decoder 
{ 
    // here the view is being allocated from the XIB. "alloc" as been called, "initWithCoder" is in progress 
    // frame is not set at this line, but as soon as we call the super implementation… 
    self = [super initWithCoder:decoder]; 
    if (self) 
    { 
    // Here all the properties of the view set in the XIB file (thru the inspector) are now applied 
    // Including the frame of the view (and its backgroundColor and all what you set thru IB) 
    // so self.frame is initialized with the correct value here 
    } 
    return self; 
} 

- (id)initWithFrame:(CGRect)frame 
{ 
    // here the view is being allocated from code. "alloc" as been called, "initWithFrame" is in progress 
    // self.frame is not set at this line, but as soon as we call the super implementation… 
    self = [super initWithFrame:frame]; 
    if (self) 
    { 
    // Here the view is initialized with its frame property 
    // so self.frame is initialized with the correct value here 
    // and you can initialize every other property from here 
    } 
    return self; 
} 
@end 

@implementation YourCustomUIViewController 
-(void)viewDidLoad 
{ 
    // At that point, the view of your UIViewController has been loaded/created 
    // (either via XIB or via the loadView method), so either its initWithCoder (if via XIB) 
    // or its initWithFrame (if via loadView) has been called 
    // so in either case, its frame has the right value 
} 

/* 
// In case your YourCustomUIViewController does not have a XIB associated with it 
// You have to implement this method to provide a view to your UIViewController by code 
-(void)loadView 
{ 
    // Create a view by code, and give it a frame 
    UIView* rootView = [[UIView alloc] initWithFrame:CGRectMake(0,0,..., ...)]; 
    rootView.backgroundColor = [UIColor redColor]; // for example 
    self.view = rootView; 
    [rootView release]; 

    // at the end of this method, self.view must be non-nil of course. 
} 
*/ 
@end 

---

（°），另一種可能性是，該觀點已被實例化，但後來解除了分配的，因爲你收到了內存不足的警告，而你的觀點是在屏幕上不那麼所使用的內存視圖已被回收。但無論如何，該視圖因此尚未加載並且必須被加載/創建