Question

我理解如何使单个图像可拖动，但我似乎无法使两个不同的图像可拖动。这是我的代码：

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

  UITouch *touch = [[event allTouches] anyObject];
  CGPoint location = [touch locationInView:self.view];

  if ([touch view] == player1) {
      player1.center = location;
  } else {
      player2.center = location;
  }

}

player1和player2是我的两张图片。

我不明白为什么上面的代码不起作用？我非常感谢任何人可以给我的任何帮助/建议。

提前致谢！

Answer 1

if ([[touch view] isEqual:player1])因为你比较的是对象，而不是原始的标量。

Answer 2

你应该做的是子类UIImageView并在那里实现touchesMoved:。因此，当您初始化可拖动视图时，它们都会继承touchesMoved:功能。你的代码看起来应该更像......

//Player.h
@interface Player : UIImageView

CGPoint startLocation;

@end

//Player.m
@implementation Player

- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {   
     // Retrieve the touch point
     CGPoint pt = [[touches anyObject] locationInView:self];
     startLocation = pt;
}

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

       CGPoint pt = [[touches anyObject] locationInView:self];
       CGFloat dx = pt.x - startLocation.x;
       CGFloat dy = pt.y - startLocation.y;
       CGPoint newCenter = CGPointMake(self.center.x + dx, self.center.y + dy);
       self.center = newCenter;
}

@end

现在，当您初始化Player时，请执行以下示例：

Player *player1 = [[Player alloc] initWithImage:[UIImage imageNamed:@"player1.png"]];
[self.view addSubview:player1];
// You can now drag player1 around your view.


Player *player2 = [[Player alloc] init];
[self.view addSubview:player2];
// You can now drag player2 around your view.

假设您将这些Players添加到UIViewController的视图中。

他们都实施-touchesMoved:

希望这有帮助！

更新：添加了-touchesBegan:，其中包含拖动子类UIImageView的完整示例，请确保将.userInteractionEnabled属性设置为是因为默认情况下 OFF 。

iOS开发 - 创建多个可拖动图像

2 个答案: