九：UIView的拖拽，九:UIView拖拽

九：UIView的拖拽，九:UIView拖拽

　　做出來效果：螢幕上的一塊UIView，點擊後能自由移動

 1 #import "GreenView.h" 2 @implementation GreenView 3 - (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event 4 { 5     UITouch *touch = [touches anyObject]; 6     CGPoint currentP = [touch locationInView:self]; 7     CGPoint previousP = [touch previousLocationInView:self]; 8     CGFloat offsetX = currentP.x - previousP.x; 9     CGFloat offsetY = currentP.y - previousP.y;10     self.transform = CGAffineTransformTranslate(self.transform, offsetX, offsetY);11 }12 @end