如何使用iPhone SDK只拖动一张图像 [英] How to drag only one image with iPhone SDK
问题描述
我想创建一个包含两个图像的小应用程序,并且我只想使图像可拖动。
经过研究,我找到了以下解决方案:
I want to create a little app that takes two images and i want to make only the image over draggable. After research, i found this solution:
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[ event allTouches] anyObject];
image.alpha = 0.7;
if([touch view] == image){
CGPoint location = [touch locationInView:self.view];
image.center = location;
}
它可以工作,但问题是图像可从其中心拖动不想那样
所以我找到了另一个解决方案:
It works but the problem is that the image is draggable from its center and I don't want that. So I found another solution:
- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
// Retrieve the touch point
CGPoint pt = [[touches anyObject] locationInView:self.view];
startLocation = pt;
[[self view] bringSubviewToFront:self.view];
}
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
// Move relative to the original touch point
CGPoint pt = [[touches anyObject] locationInView:self.view];
frame = [self.view frame];
frame.origin.x += pt.x - startLocation.x;
frame.origin.y += pt.y - startLocation.y;
[self.view setFrame:frame];
}
效果很好,但是当我添加其他图像时,视图可同时拖动。我是iPhone开发的初学者,我不知道如何只能使图像在可拖动状态。
It works very well but when I add another image, all the images of the view are draggable at the same time. I'm a beginner with the iPhone development and I have no idea of how I can only make the image over draggable.
推荐答案
您可以在 touchesBegan:
方法中使用 if
条件,请参阅此-
You can use if
condition in the touchesBegan:
method, See this-
-(void)ViewDidLoad
{
//Your First Image View
UIImageView *imageView1 = [UIImageView alloc]initWithFrame:CGRectMake(150.0, 100.0, 30.0, 30.0)];
[imageView1 setImage:[UIImage imageNamed:@"anyImage.png"]];
[imageView1 setUserInteractionEnabled:YES];
[self.view addSubview:imageView1];
//Your Second Image View
UIImageView *imageView2 = [UIImageView alloc]initWithFrame:CGRectMake(150.0, 200.0, 30.0, 30.0)];
[imageView2 setImage:[UIImage imageNamed:@"anyImage.png"]];
[imageView2 setUserInteractionEnabled:YES];
[self.view addSubview:imageView2];
}
//Now Use Touch begin methods with condition like this
- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches]anyObject];
if([touch view] == imageView1)
{
CGPoint pt = [[touches anyObject] locationInView:imageView1];
startLocation = pt;
}
if([touch view] == imageView2)
{
CGPoint pt = [[touches anyObject] locationInView:imageView2];
startLocation = pt;
}
}
//Use same thing with touch move methods...
- (void) touchesMoved:(NSSet *)touches withEvent: (UIEvent *)event
{
UITouch *touch = [[event allTouches]anyObject];
if([touch view] == imageView1)
{
CGPoint pt = [[touches anyObject] previousLocationInView:imageView1];
CGFloat dx = pt.x - startLocation.x;
CGFloat dy = pt.y - startLocation.y;
CGPoint newCenter = CGPointMake(imageView1.center.x + dx, imageView1.center.y + dy);
imageView1.center = newCenter;
}
if([touch view] == imageView2)
{
CGPoint pt = [[touches anyObject] previousLocationInView:imageView2];
CGFloat dx = pt.x - startLocation.x;
CGFloat dy = pt.y - startLocation.y;
CGPoint newCenter = CGPointMake(imageView2.center.x + dx, imageView2.center.y + dy);
imageView2.center = newCenter;
}
}
这两个图像仅在您触摸时才会移动并移动它。希望我的教程对您有所帮助。
These two images will move only when you touch on it and move it. I hope my tutorials will help you.
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