Question

iphone开发高手进来解释解释这些语句的意思，逐行解释~~多谢多谢！好的话加分！！

下面这是个拖动Button的代码实现函数：

-(IBAction)buttonMoved:(id)sender forEvent:(UIEvent *)event
{
NSSet *set = [event allTouches];
UITouch *touch = [[set allObjects] objectAtIndex:0];
CGPoint currentPoint = [touch locationInView:self.view];
CGPoint lastPoint = [touch previousLocationInView:self.view];
UIButton *btn = (UIButton*)sender;
CGRect frame = btn.frame;
btn.frame =
CGRectOffset(frame, currentPoint.x - lastPoint.x, currentPoint.y - lastPoint.y);

}

Answer 1

NSSet *set = [event allTouches]; //通过用户界面事件 返回所有点
UITouch *touch = [[set allObjects] objectAtIndex:0]; //获取第1个点因为有可能是多点触模
CGPoint currentPoint = [touch locationInView:self.view]; //获取这个点坐标
CGPoint lastPoint = [touch previousLocationInView:self.view];//获取上一次的点坐标
UIButton *btn = (UIButton*)sender;//将函数转进来的ID 强转成UIBUTTON 对象
CGRect frame = btn.frame; //创建1个和BTN 一样的FRAME
btn.frame =
CGRectOffset(frame, currentPoint.x - lastPoint.x, currentPoint.y - lastPoint.y);
//CGRectOffset使用从源CGRect偏移的原点来创建矩形 返回的新的FRAME 就是BTN 新的FRAME

注意FRAME 就是这个控件的 X，Y ，宽，高

希望能帮助到你~嘿嘿