我正在使用project，并且在尝试修复其他内容时设法破坏了UIScrollView的功能。我恢复了代码，但滚动视图仍然被打破。要找到错误，请运行项目，然后在表格视图中选择“基本查看器”。现在尝试缩放和平移可见页面......它会缩放，但不会滚动。
所以问题是滚动视图的内容偏移固定为{0,0}。 （即使在缩放之后。）并且导致它被固定的事情不是调用setContentOffset:。我已经将UIScrollView子类化为调试正在进行的操作，并且已经发现UIPanGestureRecognizer没有问题，即将正确的值发送到setContentOffset:。
滚动视图是UICollectionViewCell的子视图。这是它被添加到单元格的方式：
- (void)setPageContentView:(PDFKPageContentView *)pageContentView
{
if (_pageContentView) {
[self removeConstraints:[self constraints]];
[_pageContentView removeFromSuperview];
}
if (pageContentView == nil) {
return;
}
_pageContentView = pageContentView;
_pageContentView.translatesAutoresizingMaskIntoConstraints = NO;
[self.contentView addSubview:_pageContentView];
NSMutableArray *constraints = [[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[content]|" options:NSLayoutFormatAlignAllBaseline metrics:nil views:@{@"superview": self.contentView, @"content": _pageContentView}] mutableCopy];
[constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[content]|" options:NSLayoutFormatAlignAllLeft metrics:nil views:@{@"superview": self.contentView, @"content": _pageContentView}]];
[self.contentView addConstraints:constraints];
}
和UIScrollView子类：
@implementation PDFKPageContentView
{
PDFKPageContent *theContentView;
PDFKPageContentThumb *theThumbView;
UIView *theContainerView;
}
static void *PDFKPageContentViewContext = &PDFKPageContentViewContext;
static inline CGFloat ZoomScaleThatFits(CGSize target, CGSize source)
{
CGFloat w_scale = (target.width / source.width);
CGFloat h_scale = (target.height / source.height);
return ((w_scale < h_scale) ? w_scale : h_scale);
}
- (void)updateMinimumMaximumZoom
{
CGRect targetRect = CGRectInset(self.bounds, 0, 0);
CGFloat zoomScale = ZoomScaleThatFits(targetRect.size, theContentView.bounds.size);
//Set the minimum and maximum zoom scales
self.minimumZoomScale = zoomScale;
self.maximumZoomScale = (zoomScale * ZOOM_MAXIMUM);
}
- (id)initWithFrame:(CGRect)frame fileURL:(NSURL *)fileURL page:(NSUInteger)page password:(NSString *)phrase
{
if ((self = [super initWithFrame:frame]))
{
self.scrollsToTop = NO;
self.delaysContentTouches = NO;
self.showsVerticalScrollIndicator = NO;
self.showsHorizontalScrollIndicator = NO;
self.contentMode = UIViewContentModeRedraw;
self.backgroundColor = [UIColor clearColor];
self.userInteractionEnabled = YES;
self.autoresizesSubviews = NO;
self.pagingEnabled = NO;
self.bouncesZoom = YES;
self.delegate = self;
self.scrollEnabled = YES;
self.clipsToBounds = YES;
theContentView = [[PDFKPageContent alloc] initWithURL:fileURL page:page password:phrase];
if (theContentView != nil)
{
theContainerView = [[UIView alloc] initWithFrame:theContentView.bounds];
theContainerView.backgroundColor = [UIColor blueColor];
theContainerView.autoresizesSubviews = NO;
theContainerView.userInteractionEnabled = NO;
theContainerView.contentMode = UIViewContentModeRedraw;
theContainerView.autoresizingMask = UIViewAutoresizingNone;
theContainerView.backgroundColor = [UIColor whiteColor];
//Content size same as view size
self.contentSize = theContentView.bounds.size;
//Add the thumb view to the container view
theThumbView = [[PDFKPageContentThumb alloc] initWithFrame:theContentView.bounds]; // Page thumb view
[theContainerView addSubview:theThumbView];
//Add the content view to the container view
[theContainerView addSubview:theContentView];
//Add the container view to the scroll view
[self addSubview:theContainerView];
//Update the minimum and maximum zoom scales
[self updateMinimumMaximumZoom];
//Set zoom to fit page content
self.zoomScale = self.minimumZoomScale;
}
[self addObserver:self forKeyPath:@"frame" options:0 context:PDFKPageContentViewContext];
//Tag the view with the page number
self.tag = page;
}
return self;
}
- (void)dealloc
{
[self removeObserver:self forKeyPath:@"frame" context:PDFKPageContentViewContext];
}
- (void)showPageThumb:(NSURL *)fileURL page:(NSInteger)page password:(NSString *)phrase guid:(NSString *)guid
{
//Page thumb size
BOOL large = ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPad);
CGSize size = (large ? CGSizeMake(PAGE_THUMB_LARGE, PAGE_THUMB_LARGE) : CGSizeMake(PAGE_THUMB_SMALL, PAGE_THUMB_SMALL));
PDFKThumbRequest *request = [PDFKThumbRequest newForView:theThumbView fileURL:fileURL password:phrase guid:guid page:page size:size];
//Request the page thumb
UIImage *image = [[PDFKThumbCache sharedCache] thumbRequest:request priority:YES];
// Show image from cache
if ([image isKindOfClass:[UIImage class]]) [theThumbView showImage:image];
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
//Reset the zoom on frame change.
//Our context
if (context == PDFKPageContentViewContext) {
if ((object == self) && [keyPath isEqualToString:@"frame"]) {
CGFloat oldMinimumZoomScale = self.minimumZoomScale;
//Update zoom scale limits
[self updateMinimumMaximumZoom];
//Old minimum
if (self.zoomScale == oldMinimumZoomScale) {
self.zoomScale = self.minimumZoomScale;
} else {
// Check against minimum zoom scale
if (self.zoomScale < self.minimumZoomScale) {
self.zoomScale = self.minimumZoomScale;
} else {
// Check against maximum zoom scale
if (self.zoomScale > self.maximumZoomScale) {
self.zoomScale = self.maximumZoomScale;
}
}
}
}
}
}
- (void)layoutSubviews
{
[super layoutSubviews];
//Center the content when zoomed out
CGSize boundsSize = self.bounds.size;
CGRect viewFrame = theContainerView.frame;
if (viewFrame.size.width < boundsSize.width)
viewFrame.origin.x = (((boundsSize.width - viewFrame.size.width) / 2.0f) + self.contentOffset.x);
else
viewFrame.origin.x = 0.0f;
if (viewFrame.size.height < boundsSize.height)
viewFrame.origin.y = (((boundsSize.height - viewFrame.size.height) / 2.0f) + self.contentOffset.y);
else
viewFrame.origin.y = 0.0f;
theContainerView.frame = viewFrame;
theThumbView.frame = theContainerView.bounds;
theContentView.frame = theContainerView.bounds;
}
- (id)processSingleTap:(UITapGestureRecognizer *)recognizer
{
return [theContentView processSingleTap:recognizer];
}
- (void)zoomIncrement
{
CGFloat zoomScale = self.zoomScale;
if (zoomScale < self.maximumZoomScale) {
zoomScale *= ZOOM_FACTOR; // Zoom in
if (zoomScale > self.maximumZoomScale) {
zoomScale = self.maximumZoomScale;
}
[self setZoomScale:zoomScale animated:YES];
}
}
- (void)zoomDecrement
{
CGFloat zoomScale = self.zoomScale;
if (zoomScale > self.minimumZoomScale) {
zoomScale /= ZOOM_FACTOR; // Zoom out
if (zoomScale < self.minimumZoomScale) {
zoomScale = self.minimumZoomScale;
}
[self setZoomScale:zoomScale animated:YES];
}
}
- (void)zoomReset
{
if (self.zoomScale > self.minimumZoomScale) {
self.zoomScale = self.minimumZoomScale;
}
}
#pragma mark UIScrollViewDelegate methods
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return theContainerView;
}
#pragma mark UIResponder instance methods
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesBegan:touches withEvent:event]; // Message superclass
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesCancelled:touches withEvent:event]; // Message superclass
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesEnded:touches withEvent:event]; // Message superclass
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
[super touchesMoved:touches withEvent:event]; // Message superclass
}
- (void)setBounds:(CGRect)bounds
{
if (bounds.size.width != 0 && bounds.size.height == 0) {
[super setBounds: bounds];
}
}
@end
在项目中，我已经覆盖了UIScrollView的setContentOffset:，setContentSize:，setFrame:和setBounds:来打印调试信息，一切看起来都很正常。< / p>
我很难过，多谢那些可以帮我解决这个问题的人。