当我触摸UIVIew时，CALayer / UIView崩溃

UIView

CALayer

- (void) layoutSubView {
    if (drawLayer == nil) {
        drawLayer = [[CALayer alloc] init];
        [drawLayer setDelegate:self];
        [[self layer] addSublayer:drawLayer];
    }
    [drawLayer setFrame:[self bounds]]; 
    [drawLayer setNeedsDisplay];
}

- (void) drawLayer:(CALayer *)layer 
     inContext:(CGContextRef)ctx {

        if (layer == drawLayer) {
        UIGraphicsPushContext(ctx);
        [self drawTitle:ctx];
        UIGraphicsPopContext();
    }
}