我正在使用以下代码来移动 UIView 中存在的 UIImageView。
- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer {
CGPoint translation = [recognizer translationInView:self.view];
recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}
我想让 UIView 不会移动到父视图之外。此刻，图像视图能够在整个屏幕上移动。
首先获取您的新框架UIImageView并使用方法检查它是否完全在其 superView 内CGRectContainsRect()。如果是，则将UImageView's框架设置为新框架。
- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer {
CGPoint translation = [recognizer translationInView:self.view];
CGRect recognizerFrame = recognizer.view.frame;
recognizerFrame.origin.x += translation.x;
recognizerFrame.origin.y += translation.y;
// Check if UIImageView is completely inside its superView
if (CGRectContainsRect(self.view.bounds, recognizerFrame)) {
recognizer.view.frame = recognizerFrame;
}
// Else check if UIImageView is vertically and/or horizontally outside of its
// superView. If yes, then set UImageView's frame accordingly.
// This is required so that when user pans rapidly then it provides smooth translation.
else {
// Check vertically
if (recognizerFrame.origin.y < self.view.bounds.origin.y) {
recognizerFrame.origin.y = 0;
}
else if (recognizerFrame.origin.y + recognizerFrame.size.height > self.view.bounds.size.height) {
recognizerFrame.origin.y = self.view.bounds.size.height - recognizerFrame.size.height;
}
// Check horizantally
if (recognizerFrame.origin.x < self.view.bounds.origin.x) {
recognizerFrame.origin.x = 0;
}
else if (recognizerFrame.origin.x + recognizerFrame.size.width > self.view.bounds.size.width) {
recognizerFrame.origin.x = self.view.bounds.size.width - recognizerFrame.size.width;
}
}
// Reset translation so that on next pan recognition
// we get correct translation value
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}
确保您通过bounds了 superView 和frameofUIImageView以便两者CGRects都在同一个坐标系中。
尝试：
- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer
{
if (gesture.state==UIGestureRecognizerStateChanged || gesture.state == UIGestureRecognizerStateEnded){
UIView *superview = recognizer.view.superview;
CGSize superviewSize = superview.bounds.size;
CGSize thisSize = recognizer.view.size;
CGPoint translation = [recognizer translationInView:self.view];
CGPoint center = CGPointMake(recognizer.view.center.x + translation.x,
recognizer.view.center.y + translation.y);
CGPoint resetTranslation = CGPointMake(translation.x, translation.y);
if(center.x - thisSize.width/2 < 0)
center.x = thisSize.width/2;
else if (center.x + thisSize.width/2 > superviewSize.width)
center.x = superviewSize.width-thisSize.width/2;
else
resetTranslation.x = 0; //Only reset the horizontal translation if the view *did* translate horizontally
if(center.y - thisSize.height/2 < 0)
center.y = thisSize.height/2;
else if(center.y + thisSize.height/2 > superviewSize.height)
center.y = superviewSize.height-thisSize.height/2;
else
resetTranslation.y = 0; //Only reset the vertical translation if the view *did* translate vertically
recognizer.view.center = center;
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}
}
这样它就永远不会移出父视图边界，如果你试图将它移出边界，它只会“粘”在边缘！
快速版本的 micantox 答案
let gesture = UIPanGestureRecognizer(target: self, action: #selector(self.wasDragged(gestureRecognizer:)))
imageView.addGestureRecognizer(gesture)
imageView.isUserInteractionEnabled = true
@objc func wasDragged(gestureRecognizer: UIPanGestureRecognizer) {
if gestureRecognizer.state == UIGestureRecognizerState.changed || gestureRecognizer.state == UIGestureRecognizerState.ended {
let superview = gestureRecognizer.view?.superview
let superviewSize = superview?.bounds.size
let thisSize = gestureRecognizer.view?.frame.size
let translation = gestureRecognizer.translation(in: self.view)
var center = CGPoint(x: gestureRecognizer.view!.center.x + translation.x, y: gestureRecognizer.view!.center.y + translation.y)
var resetTranslation = CGPoint(x: translation.x, y: translation.y)
if center.x - (thisSize?.width)!/2 < 0 {
center.x = (thisSize?.width)!/2
} else if center.x + (thisSize?.width)!/2 > (superviewSize?.width)! {
center.x = (superviewSize?.width)!-(thisSize?.width)!/2
} else {
resetTranslation.x = 0 //Only reset the horizontal translation if the view *did* translate horizontally
}
if center.y - (thisSize?.height)!/2 < 0 {
center.y = (thisSize?.height)!/2
} else if center.y + (thisSize?.height)!/2 > (superviewSize?.height)! {
center.y = (superviewSize?.height)!-(thisSize?.height)!/2
} else {
resetTranslation.y = 0 //Only reset the vertical translation if the view *did* translate vertically
}
gestureRecognizer.view?.center = center
gestureRecognizer.setTranslation(CGPoint(x: 0, y: 0), in: self.view)
}
}
仅当它位于其父视图的内部时，您才必须将其设置recognizer.view.center为新值。使用on和来验证它们是否被包含。frameboundsCGRectContainsRectrecognizer.view.superview.boundsrecognizer.view.frame
如果要允许图像视图移动到其父视图之外，直到视图的中心点超出父视图的范围，您可以使用convertPoint:toViewof 方法UIView并验证新视图是否超出父视图CGPoint的范围。
if (gesture.state==UIGestureRecognizerStateChanged){
CGPoint translation = [recognizer translationInView:self.view];
CGRect rectToCheck=CGRectMake(yourView.frame.origin.x+translation.x, yourView.frame.origin.y+translation.y, CGRectGetWidth(yourView.frame), CGRectGetHeight(yourView.frame));
if(CGRectContainsRect(self.view.bounds,rectToCheck))// check that the rect that is going to form lies within the bounds of self.view
{
yourView.frame=CGRectMake(yourView.frame.origin.x+translation.x, yourView.frame.origin.y+translation.y, CGRectGetWidth(yourView.frame), CGRectGetHeight(yourView.frame));
}
[gesture setTranslation:CGPointZero yourView]; // important to set this
}
PS 使用手势状态块来启动、平移、移除。即 UIGestureRecognizerStateBegan UIGestureRecognizerStateChanged UIGestureRecognizerStateEnded