iPhone：如何在TouchesMoved事件上製作透明圖像？

Question

我已經嘗試過kCGBlendModeXOR，但它在透明後變黑。

這裏我的代碼，我做了，但它不是我想要的。

UITouch *touch = [touches anyObject]; 
    CGPoint currentPoint = [touch locationInView:self.view]; 
    CGPoint lastPoint = [touch locationInView: [UIApplication sharedApplication].keyWindow]; 
    UIGraphicsBeginImageContext(self.view.frame.size); 
    CGRect rect = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height); 
    [imageView_skype.image drawInRect:rect]; 
    CGContextRef context = UIGraphicsGetCurrentContext(); 

    CGContextSetLineCap(context, kCGLineCapRound); 
    CGContextSetLineWidth(context, 36.0); 
    CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0); 
    CGContextSetAlpha(context,0.10); 

    CGContextSetBlendMode(context, kCGBlendModeXOR); 

    CGContextBeginPath(context); 

    CGContextMoveToPoint(context, lastPoint.x, lastPoint.y); 
    CGContextAddLineToPoint(context, currentPoint.x, currentPoint.y); 
    CGContextStrokePath(context); 
    imageView_skype.image = UIGraphicsGetImageFromCurrentImageContext(); 

Answer 1

您可以用做面膜在你觸摸這

http://developer.apple.com/library/ios/#documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_images/dq_images.html

移動事件畫遮掩圖像只有黑色和白色

和掩蓋你的原始圖像