在我的代码中，我有一个对象数组，它们是 UIImageViews，其中包含 UIImages。
我在-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 中使用了一个 for 循环来将数组中的所有对象一个接一个地移动。
一旦它们被移动到主视图上的不同位置，我希望能够抓取任何这些对象并将它们移动到其他地方。
我不确定如何最好地做到这一点。有没有办法可以使用 touchesbegin 以便只能拖动我点击的项目？
基本上，现在有五个 UIImageViews，每个都有 UIImage，我试图达到当我点击其中任何一个时它们能够移动的地步。
【问题讨论】：
标签： iphone objective-c ios xcode
编辑：John Muchow 在博客 here 上发布了这篇文章。你应该能够适应你自己的目的。
//UIDraggableImageView.h
#import <UIKit/UIKit.h>
@interface UIDraggableImageView : UIImageView
{
CGPoint currentPoint;
}
@end
//UIDraggableImageView.m
#import "UIDraggableImageView.h"
@implementation UIDraggableImageView
- (id)initWithImage:(UIImage *)image
{
if (self = [super initWithImage:image]) {
self.userInteractionEnabled = YES;
}
return self;
}
-(void)dealloc {
[super dealloc];
}
- (void) touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event
{
// When a touch starts, get the current location in the view
currentPoint = [[touches anyObject] locationInView:self];
}
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
// Get active location upon move
CGPoint activePoint = [[touches anyObject] locationInView:self];
// Determine new point based on where the touch is now located
CGPoint newPoint = CGPointMake(self.center.x + (activePoint.x - currentPoint.x),
self.center.y + (activePoint.y - currentPoint.y));
//--------------------------------------------------------
// Make sure we stay within the bounds of the parent view
//--------------------------------------------------------
float midPointX = CGRectGetMidX(self.bounds);
// If too far right...
if (newPoint.x > self.superview.bounds.size.width - midPointX)
newPoint.x = self.superview.bounds.size.width - midPointX;
else if (newPoint.x < midPointX) // If too far left...
newPoint.x = midPointX;
float midPointY = CGRectGetMidY(self.bounds);
// If too far down...
if (newPoint.y > self.superview.bounds.size.height - midPointY)
newPoint.y = self.superview.bounds.size.height - midPointY;
else if (newPoint.y < midPointY) // If too far up...
newPoint.y = midPointY;
// Set new center location
self.center = newPoint;
}
@end
【讨论】：
我在可拖动视图中使用UIPanGestureRecognizer 做了类似的事情并取得了巨大成功。要连接它，它可能看起来像这样：
@implementation DraggableView
-(id)initWithFrame:(CGRect)frame
{
...
...
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)] autorelease];
[self addGestureRecognizer:panGesture];
..
return self;
}
@end
在您的pan: 方法中，您可以检查手势的状态，甚至捕获手势的位置并使用它来重新定位您的视图。下面是一个粗略示例：
-(void)pan:(UIPanGestureRecognizer *)gesture
{
if (gesture.state==UIGestureRecognizerStateChanged)
{
//We're moving!
UIView *aRootView = <perhaps your root view controller's view>;
CGPoint currentOrigin = [gesture translationInView:aRootView];
self.frame = CGRectMake(currentOrigin.x,currentOrigin.y,self.frame.size.width,self.frame.size.hight);
...
...
}
}
Here is more readingUIPanGestureRecognizer。
【讨论】：
您可能需要考虑将手势识别器添加到要移动的视图中，这样您就可以轻松判断它们何时被点击，并且可以使用 touchesMoved 来移动它们...
【讨论】：
单击按钮将图像从相机胶卷添加到图像视图。图片可以放大和缩小，并且应该将该图片拖到视图中的任何位置。
【讨论】：