Question

我正在为我的iPad应用程序构建一个交互式anagram功能，并且我正在尝试使用touchmove事件来使所选项目顺利地跟随运动，但它出现了一些奇怪的原因。

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    UITouch *touch = [touches anyObject];
    NSString *touchClass = [NSString stringWithFormat:@"%@",[[touch view] class]];

    if ([touchClass isEqualToString:[NSString stringWithFormat:@"%@",[AnagramLetter class]]]) {
        NSLog(@"start moving");
    }
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    NSString *touchClass = [NSString stringWithFormat:@"%@",[[touch view] class]];
    CGPoint location = [touch locationInView:touch.view];
    if ([touchClass isEqualToString:[NSString stringWithFormat:@"%@",[AnagramLetter class]]]) {
        NSLog(@"touch view centre (x,y) - (%f,%f)",touch.view.center.x,touch.view.center.y);
        NSLog(@"location (x,y) - (%f,%f)",location.x,location.y);
        touch.view.center = location;
    }
}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
    UITouch *touch = [touches anyObject];
    NSString *touchClass = [NSString stringWithFormat:@"%@",[[touch view] class]];

    if ([touchClass isEqualToString:[NSString stringWithFormat:@"%@",[AnagramLetter class]]]){
        NSLog(@"Now stop moving!");
    }
}

以上是我的3种触摸方法，看起来它们应该可以正常工作。您可以在touchesMoved方法中看到我正在检查以查看正在移动的对象是否属于特定类（我为同一个项目创建的自定义类）。有没有人知道为什么会这样？它跟随光标在模拟器中，但它似乎在跟随光标之前捕捉到底角，所以它基本上是在屏幕上跳跃。

有什么想法吗？

Answer 1

我认为问题在于您正在处理相对于被触摸的子视图的触摸。

[touch locationInView:[touch.view superview]];

会为您提供一个位置，以引用您的自定义视图的父级。

在touchesMoved方法中，您可以查看位移并将相同的位移应用于视图

if ([touchClass isEqualToString:[NSString stringWithFormat:@"%@",[AnagramLetter class]]]) {
        UITouch * touch = [touches anyObject];
        CGPoint previous = [touch previousLocationInView:[touch.view superview]];
        CGPoint current = [touch locationInView:[touch.view superview]];
        CGPoint displacement = CGPointMake(current.x - previous.x, current.y - previous.y);

        CGPoint center = touch.view.center;
        center.x += displacement.x;
        center.y += displacement.y;
        touch.view.center = center;
}

iphone拖放奇怪的跳跃运动

1 个答案: