iOS中的基本拖放 [英] Basic Drag and Drop in iOS

问题描述

我想要一个视图，其中有车辆在周围行驶，用户也可以拖放.你认为最好的大规模战略是什么?最好是从代表车辆的视图中还是从更大的视图中获取触摸事件?是否有您满意的用于拖放的简单范例?不同策略的缺点是什么?

I want to have a view in which there are vehicles driving around that the user can also drag and drop. What do you think is the best large-scale strategy for doing this? Is it best to get touch events from the views representing the vehicles, or from the larger view? Is there a simple paradigm you've used for drag and drop that you're satisfied with? What are the drawbacks of different strategies?

推荐答案

假设你有一个 UIView 场景，其中有一张背景图片和许多 vehicles，你可以定义每个新的车辆作为 UIButton (UIImageView 可能也可以工作):

Assume you have a UIView scene with a background image and many vehicles, you may define each new vehicle as a UIButton (UIImageView will probably work too):

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button addTarget:self action:@selector(imageTouch:withEvent:) forControlEvents:UIControlEventTouchDown];
[button addTarget:self action:@selector(imageMoved:withEvent:) forControlEvents:UIControlEventTouchDragInside];
[button setImage:[UIImage imageNamed:@"vehicle.png"] forState:UIControlStateNormal];
[self.view addSubview:button];

然后您可以通过响应 UIControlEventTouchDragInside 事件将车辆移动到任何您想要的位置，例如:

Then you may move the vehicle wherever you want, by responding to the UIControlEventTouchDragInside event, e.g.:

- (IBAction) imageMoved:(id) sender withEvent:(UIEvent *) event
{
    CGPoint point = [[[event allTouches] anyObject] locationInView:self.view];
    UIControl *control = sender;
    control.center = point;
}

与管理整个场景相比，单个车辆处理自己的阻力要容易得多.

It's a lot easier for individual vehicle to handle its own drags, comparing to manage the scene as a whole.

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