修改
我将我的实施上传到github。也许最好先了解我想要什么以及我的问题是什么。 我在github项目中的代码比这里发布的代码稍微改了一些。我认为github项目中的实现更好，但并不完美。
我想做什么：
拥有带可移动UIViews的UIScrollView（例如图像）。用户可以平移此子视图并放大和缩小。当用户放大并在当前可见区域上移动子视图时，scrollView应自动滚动。由于子视图位于边缘，因此scrollview应滚动。当子视图不再在可见区域上时，滚动视图应该停止移动。
我试着尽可能好地解释我的问题。
我设法做了什么：
缩放滚动视图，使用UIPanGestureRecognizer移动子视图，识别子视图何时在可见区域上并开始移动（更改contentOffset）scrollview。只要子视图在可见区域上，我就可以使用NSTimer移动滚动视图。
我的问题：
当子视图在可见区域上时，启动NSTimer，以更改子视图的contentOffset和子视图的帧（位置）。 在那之后我再也无法平移子视图了。 我无法弄清楚如何以正确的方式更改子视图帧来实现平移手势。
我的实施：
我使用三种观点：
目前，MyImageContainerView管理工作流程。 MyImageView附加了UIPanGestureRecognizer。此识别器的方法在MyImageContainerView中实现：
- (void)handlePanGesture:(UIPanGestureRecognizer *)gestureRecognizer
{
//UIView which is moved by the user
MyImageView *currentView = gestureRecognizer.view;
switch (gestureRecognizer.state)
{
case UIGestureRecognizerStatePossible:
{
break;
}
case UIGestureRecognizerStateBegan:
{
//save both values in global instance variables
currentFrameOriginX = currentView.frame.origin.x;
currentFrameOriginY = currentView.frame.origin.y;
//global BOOL variable, to check if scrollView movement is performed
scrolling = NO;
break;
}
case UIGestureRecognizerStateChanged:
{
CGRect rect = CGRectMake(currentFrameOriginX + [gestureRecognizer translationInView:currentView.superview].x, currentFrameOriginY + [gestureRecognizer translationInView:currentView.superview].y, currentView.frame.size.width, currentView.frame.size.height);
if (CGRectContainsRect(currentView.superview.frame, rect)) {
/*PROBLEM: Here is a problem. I need this change of the frame here, to move the UIView along the movement from the user. In my autoScroll-method I have to set the frame of currentView, too. But I can't set the frame of currentView here and in the autoScroll. But as long as the NSTimer runs and is calling autoScroll: this if-statement isn't called, so I can't move the UIView with my finger anymore. */
if (!scrolling) {
//currently the NSTimer method for the automatically scrolling isn't performed, so:
//change the frame according to the pan gesture
currentView.frame = rect;
}
UIScrollView *scrollView = self.myScrollView; //reference to the "root" UIScrollView
CGRect visibleRect;
visibleRect.origin = scrollView.contentOffset;
visibleRect.size = scrollView.bounds.size;
CGRect frame = currentView.frame;
CGFloat scale = 1.0 / scrollView.zoomScale;
visibleRect.origin.x *= scale;
visibleRect.origin.y *= scale;
visibleRect.size.width *= scale;
visibleRect.size.height *= scale;
CGSize scrollZone = CGSizeMake(10.0f, 10.0f);
float scrollStep = 3.0f;
CGPoint scrollAmount = CGPointZero;
//determine the change of x and y
if (frame.origin.x+scrollZone.width < visibleRect.origin.x) {
scrollAmount.x = -scrollStep;
}
else if((frame.origin.x+frame.size.width)-scrollZone.width > visibleRect.origin.x + visibleRect.size.width) {
scrollAmount.x = scrollStep;
}
else if (frame.origin.y+scrollZone.height < visibleRect.origin.y) {
scrollAmount.y = -scrollStep;
}
else if((frame.origin.y+frame.size.height)-scrollZone.height > visibleRect.origin.y + visibleRect.size.height) {
scrollAmount.y = scrollStep;
}
if ((scrollAmount.x != 0) | (scrollAmount.y != 0)) {
if (![scrollTimer isValid]) {
//scrollTimer is a global NSTimer instance variable
[scrollTimer invalidate];
scrollTimer = nil;
NSString *scrollString = NSStringFromCGPoint(scrollAmount);
NSDictionary *info = [NSDictionary dictionaryWithObjectsAndKeys:scrollString, @"scrollString", currentView, @"currentView", nil];
scrollTimer = [[NSTimer alloc]initWithFireDate:[NSDate date] interval:0.03f target:self selector:@selector(autoScroll:) userInfo:info repeats:YES];
[[NSRunLoop mainRunLoop] addTimer:scrollTimer forMode:NSRunLoopCommonModes];
}
}
else {
[scrollTimer invalidate];
scrollTimer = nil;
scrolling = NO;
}
}
break;
}
case UIGestureRecognizerStateEnded:
{
//quite know the scrolling should stop, maybe it would be better when the scrollView scrolls even if the user does nothing when the subview is over the visible area
[scrollTimer invalidate];
scrollTimer = nil;
scrolling = NO;
break;
}
default:
{
[scrollTimer invalidate];
scrollTimer = nil;
scrolling = NO;
break;
}
}
}
-(void)autoScroll:(NSTimer*)timer {
scrolling = YES; //the scroll method is executed quite know
NSDictionary *info = [timer userInfo];
UIScrollView *scrollView = self.myScrollView;
CGRect visibleRect;
visibleRect.origin = scrollView.contentOffset;
visibleRect.size = scrollView.bounds.size;
CGPoint scrollAmount = CGPointFromString([info objectForKey:@"scrollString"]);
MyImageView *currentView = [info objectForKey:@"currentView"];
//stop scrolling when the UIView is at the edge of the containerView (referenced over 'self')
if ((currentView.frame.origin.x <= 0 | currentView.frame.origin.y <= 0) ||
((currentView.frame.origin.x+currentView.frame.size.width) > self.frame.size.width | (currentView.frame.origin.y+currentView.frame.size.height) > self.frame.size.height)
) {
scrolling = NO;
return;
}
//move the UIView
CGFloat scale = 1.0 / scrollView.zoomScale;
if (scrollAmount.x != 0) {
scrollAmount.x *= scale;
}
if (scrollAmount.y != 0) {
scrollAmount.y *= scale;
}
CGRect frame = currentView.frame;
frame.origin.x += scrollAmount.x;
frame.origin.y += scrollAmount.y;
currentView.frame = frame;
currentFrameOriginX = currentView.frame.origin.x;
currentFrameOriginY = currentView.frame.origin.y;
//move the scrollView
CGPoint contentOffset = scrollView.contentOffset;
contentOffset.x += scrollAmount.x;
contentOffset.y += scrollAmount.y;
[scrollView setContentOffset:contentOffset animated:NO];
}