是否可以停止CATiledLayer绘制(drawLayer：inContext)？
它异步绘制,当我尝试释放CATiledLayer使用的CGPDFDocumentRef时,应用程序崩溃(EXC_BAD_ACCESS).
它异步绘制,当我尝试释放CATiledLayer使用的CGPDFDocumentRef时,应用程序崩溃(EXC_BAD_ACCESS).
这是我的看法
@implementation TiledPDFView
- (id)initWithFrame:(CGRect)frame andScale:(CGFloat)scale{
if ((self = [super initWithFrame:frame])) {
CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
tiledLayer.levelsOfDetail = 4;
tiledLayer.levelsOfDetailBias = 4;
tiledLayer.tileSize = CGSizeMake(512.0,512.0);
myScale = scale;
}
return self;
}
// Set the layer's class to be CATiledLayer.
+ (Class)layerClass {
return [CATiledLayer class];
}
- (void)stopDrawing{
CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
[tiledLayer removeFromSuperlayer];
tiledLayer.delegate = nil;
}
// Set the CGPDFPageRef for the view.
- (void)setPage:(CGPDFPageRef)newPage
{
CGPDFPageRelease(self->pdfPage);
self->pdfPage = CGPDFPageRetain(newPage);
//self->pdfPage = newPage;
}
-(void)drawRect:(CGRect)r
{
}
// Draw the CGPDFPageRef into the layer at the correct scale.
-(void)drawLayer:(CALayer*)layer inContext:(CGContextRef)context
{
// First fill the background with white.
CGContextSetRGBFillColor(context,1.0,1.0);
CGContextFillRect(context,self.bounds);
CGContextSaveGState(context);
// Flip the context so that the PDF page is rendered
// right side up.
CGContextTranslateCTM(context,0.0,self.bounds.size.height);
CGContextScaleCTM(context,-1.0);
// Scale the context so that the PDF page is rendered
// at the correct size for the zoom level.
CGContextScaleCTM(context,myScale,myScale);
CGContextDrawPDFPage(context,pdfPage);
CGContextRestoreGState(context);
}
// Clean up.
- (void)dealloc {
CGPDFPageRelease(pdfPage);
[super dealloc];
}
这是我试图在视图控制器中停止和发布PDF的地方：
v是TiledPDFView的实例
-(void) stopDwaring {
[v stopDrawing];
[v removeFromSuperview];
[v release];
[self.view removeFromSuperview];
self.view = nil;
CGPDFDocumentRelease(pdf);
}
解决方法
这篇文章帮助我解决了我自己的麻烦与CATiledLayer.我以Apple的文档中的TiledPDFview.m为例.
由于我需要在某个时候重绘整个视图和所有的图块,所以我使用CATiledLayer作为属性.
当退出并取消分配视图控制器时,它使用[CATiledLayer retain]：发送到释放的实例的消息崩溃.
这是我的dealloc方法的视图控制器：
由于我需要在某个时候重绘整个视图和所有的图块,所以我使用CATiledLayer作为属性.
当退出并取消分配视图控制器时,它使用[CATiledLayer retain]：发送到释放的实例的消息崩溃.
这是我的dealloc方法的视图控制器：
- (void)dealloc {
self.tiledLayer.contents=nil;
self.tiledLayer.delegate=nil;
[self.tiledLayer removeFromSuperlayer];
// note: releasing the layer still crashes-
// I guess removeFromSuperlayer releases it already,// but couldn't find documentation so far.
// So that's why it's commented out:
// [self.tiledLayer release],self.tiledLayer=nil;
//release the other viewcontroller stuff...
[super dealloc];
}
这对我行得通.希望它有助于某人.
