iPhone iOS4上的內存泄漏？

Question

我有將UILabel添加到我的視圖的功能：

UILabel* AddLabel(UIView* view,CGRect labelRect, UIStyle* labelStyle, NSString* labelText)
{
    UILabel* label = [[[UILabel alloc] initWithFrame:labelRect] autorelease];
    label.textColor = [UIColor colorWithCGColor:[ labelStyle.textColor CGColor]];
    label.backgroundColor = [UIColor colorWithCGColor:[labelStyle.backgroundColor CGColor]];
    label.font =[UIFont fontWithName: labelStyle.fontName] size:labelStyle.fontSize];

    label.frame = labelRect;
    label.text = labelText;
    [view addSubview:label];
    return label;
}

其中UIStyle有這個接口：

@interface UIStyle : NSObject {
    NSString * fontName;
    CGFloat fontSize;
    UIColor* textColor;
    UIColor* backgroundColor;
}

所以當我添加這樣的標簽來查看時，我得到了內存泄漏。 以下是儀器的描述：

   0 libSystem.B.dylib calloc
   1 CoreGraphics CGGlyphBitmapCreate
   2 CoreGraphics CGFontCreateGlyphBitmap8
   3 CoreGraphics CGFontCreateGlyphBitmap
   4 CoreGraphics create_missing_bitmaps
   5 CoreGraphics CGGlyphLockLockGlyphBitmaps
   6  0x317c173f
   7  0x317c3e59
   8 CoreGraphics CGContextDelegateDrawGlyphs
   9 CoreGraphics draw_glyphs
  10 CoreGraphics CGContextShowGlyphsWithAdvances
  11 WebCore WebCore::Font::drawGlyphs(WebCore::GraphicsContext*, WebCore::SimpleFontData const*, WebCore::GlyphBuffer const&, int, int, WebCore::FloatPoint const&, bool) const
  12 WebCore WebCore::Font::drawGlyphBuffer(WebCore::GraphicsContext*, WebCore::GlyphBuffer const&, WebCore::TextRun const&, WebCore::FloatPoint&) const
  13 WebCore WebCore::Font::drawSimpleText(WebCore::GraphicsContext*, WebCore::TextRun const&, WebCore::FloatPoint const&, int, int) const
  14 WebCore WebCore::Font::drawText(WebCore::GraphicsContext*, WebCore::TextRun const&, WebCore::FloatPoint const&, int, int) const
  15 WebCore drawAtPoint(unsigned short const*, int, WebCore::FloatPoint const&, WebCore::Font const&, WebCore::GraphicsContext*, WebCore::BidiStatus*, int)
  16 WebCore -[NSString(WebStringDrawing) __web_drawInRect:withFont:ellipsis:alignment:letterSpacing:lineSpacing:includeEmoji:truncationRect:measureOnly:]
  17 WebCore -[NSString(WebStringDrawing) _web_drawInRect:withFont:ellipsis:alignment:lineSpacing:includeEmoji:truncationRect:measureOnly:]
  18 WebCore -[NSString(WebStringDrawing) _web_drawInRect:withFont:ellipsis:alignment:lineSpacing:includeEmoji:truncationRect:]
  19 UIKit -[NSString(UIStringDrawing) _drawInRect:withFont:lineBreakMode:alignment:lineSpacing:includeEmoji:truncationRect:]
  20 UIKit -[NSString(UIStringDrawing) drawInRect:withFont:lineBreakMode:alignment:lineSpacing:includeEmoji:]
  21 UIKit -[NSString(UIStringDrawing) drawInRect:withFont:lineBreakMode:alignment:lineSpacing:]
  22 UIKit -[UILabel _drawTextInRect:baselineCalculationOnly:]
  23 UIKit -[UILabel drawTextInRect:]
  24 UIKit -[UILabel drawRect:]
  25 UIKit -[UIView(CALayerDelegate) drawLayer:inContext:]
  26 QuartzCore -[CALayer drawInContext:]
  27 QuartzCore backing_callback(CGContext*, void*)
  28 QuartzCore CABackingStoreUpdate
  29 QuartzCore -[CALayer _display]
  30 QuartzCore -[CALayer display]
  31 QuartzCore CALayerDisplayIfNeeded
  32 QuartzCore CA::Context::commit_transaction(CA::Transaction*)
  33 QuartzCore CA::Transaction::commit()
  34 QuartzCore CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*)
  35 CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__
  36 CoreFoundation __CFRunLoopDoObservers
  37 CoreFoundation __CFRunLoopRun
  38 CoreFoundation CFRunLoopRunSpecific
  39 CoreFoundation CFRunLoopRunInMode
  40 GraphicsServices GSEventRunModal
  41 GraphicsServices GSEventRun
  42 UIKit -[UIApplication _run]
  43 UIKit UIApplicationMain
  44 Cuisine main /iPhone/Projects/iCookProFullSix/iCookPrototype/main.m:14

我有幾百個用於函數AddLabel的多次調用。 我這樣稱呼它：

AddLabel(self.view, CGRectMake(56, 60, 88, 15), style2, @"text");

問題是，如果我評論label.font =[UIFont fontWithName: labelStyle.fontName] size:labelStyle.fontSize]; - 沒有泄漏..

為什么會這樣？ 這是iOS的錯誤還是我做錯了什么？

PS此泄漏僅在設備上可見。

有人可以幫忙嗎？ 提前致謝！

Answer 1

除非您創建的每個UIFont都發生此泄漏，否則不必擔心 - 操作系統將在您的應用程序退出時清除泄漏。

如果每次創建UIFont時都會出現，可能你的UIStyle類（順便UIFont Apple的命名空間）應該緩存UIFont而不是重新創建它。

另外，你不需要[UIColor colorWithCGColor:[labelStyle.textColor CGColor]]位，你可以只指定labelStyle.textColor

Answer 2

嘗試保留返回的UIfont，並手動釋放它。

我剛試過這個，它似乎為我解決了。

Answer 3

引起內存泄漏是因為UIStyle類沒有正確保留和釋放字體名稱。 它應該是：

@interface UIStyle : NSObject {
  NSString * fontName;
  CGFloat fontSize;
  UIColor* textColor;
  UIColor* backgroundColor;
}
@property(nonatomic, retain) NSString* fontName;
...

另外，在UIStyle實現文件中，該屬性應該合成並在dealloc函數中釋放。

Answer 4

基於對UIFont文檔的閱讀，我的理解是在內部緩存字體對象，以便將來可以更快地查找相同字體。 我確信內存中的損失相當小，而且可能泄漏似乎實際上是設計的，所以不用擔心。