iPhone：UIImage中如何設置Alpha觸摸PIxel？

Question

- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ 


    NSSet *allTouches = [[event allTouches] retain]; 
    switch ([allTouches count]) 
    { 
      case 1: { 
      UITouch *touch = [[allTouches allObjects] objectAtIndex:0]; 
      CGPoint touchPoint = [touch locationInView:[self view]]; 
       if(touchPoint.x > rightleg.frame.origin.x && touchPoint.x < rightleg.frame.origin.x + rightleg.frame.size.width && 
        touchPoint.y > rightleg.frame.origin.y && touchPoint.y < rightleg.frame.origin.y + rightleg.frame.size.height){ 
        rightleg.alpha = rightleg.alpha + 0.005; 
       } 
      } 
     case 2 :{ 
      UITouch *touch = [[allTouches allObjects] objectAtIndex:0]; 
      CGPoint touchPoint = [touch locationInView:[self view]]; 
      if(touchPoint.x > leftleg.frame.origin.x && touchPoint.x < leftleg.frame.origin.x + leftleg.frame.size.width && 
       touchPoint.y > leftleg.frame.origin.y && touchPoint.y < leftleg.frame.origin.y + leftleg.frame.size.height){ 
       leftleg.alpha = leftleg.alpha + 0.005; 

      } 
     } 
    } 


} 

當用戶觸摸圖像時，此代碼在UIImage上設置爲alpha，但是如何在觸摸該像素時在UIImage中的像素上設置alpha？

Answer 1

您將不得不將UIImage轉換爲字節數組，然後進行更改，然後再保存到UIImage。

像這樣的東西可能會有所幫助：

• http://brandontreb.com/image-manipulation-retrieving-and-updating-pixel-values-for-a-uiimage/

• Can I edit the pixels of the UIImage's property CGImage