在非arc與arc的環境中使用時，導致程序crash.

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1 //當前類使用－fno-objc 編譯 2 3 needle_ = [[MyView alloc] init]; 4 5 needleLayer = [CALayer layer]; 6 needleLayer.delegate = self.needle; 7 8 9 - (void)dealloc 10 { 11 [needle_ release]; 12 [needleLayer release]; 13 [super dealloc]; //crash 14 } 15

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1 -(void) drawLayer: (CALayer*) layer inContext: (CGContextRef) context

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he lightest-wight solution would be to create a small helper class in the the file as the UIView that's using the CALayer:

In MyView.h

@interfaceMyLayerDelegate:NSObject...@end

In MyView.m

@implementationMyLayerDelegate-(void)drawLayer:(CALayer*)layer inContext:(CGContextRef)ctx {...}@end

Just place those at the top of your file, immediately below the #import directives. That way it feels more like using a "private class" to handle the drawing (although it isn't -- the delegate class can be instantiated by any code that imports the header).

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Feedback #1樓 2012-11-09 11:51?|?為了誰?? needleLayer.delegate = nil;這句話寫在dealloc中，因為CALayer中的delegate是assign的屬性，這樣你釋放[needle_ release];后，deletate就是野指針了。在arc中如果有weak了，如果delegatej是weak的屬性，就不會crash..

我們在程序設計中也要注意傳指針。 支持(0)反對(0)
??回復引用刪除 #2樓[樓主] 2012-11-14 15:07?|?不及格的程序員-八神?? @?為了誰
請教一下，為什么視圖已經在delloc中了，它還會訪問用CALayer的delegate呢？ 支持(0)反對(0)

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