【发布时间】：2014-05-14 10:37:28
【问题描述】：
我正在使用此代码水平滚动页面，但出现此错误： 由于未捕获的异常“NSUnknownKeyException”而终止应用程序，原因：“[<__nscfstring> valueForUndefinedKey:]：此类与键图像的键值编码不兼容。”
为什么会出现此错误以及如何纠正此错误。
-(void)loadScrollView
{
_scrollView.contentSize = CGSizeMake(0, _scrollView.frame.size.height);
// [[SharedUtilities getInstance]RemoveActivityIndicatorView];
NSMutableArray *controllers1 = [[NSMutableArray alloc] init];
for (unsigned i = 0; i < [_arrUrlLinks count]; i++) {
[controllers1 addObject:[NSNull null]];
}
self.viewControllers1 = controllers1;
count=1;
// a page is the width of the scroll view
_scrollView.pagingEnabled = YES;
_scrollView.contentSize = CGSizeMake(_scrollView.frame.size.width * [_arrUrlLinks count], _scrollView.frame.size.height);
_scrollView.showsHorizontalScrollIndicator = NO;
_scrollView.showsVerticalScrollIndicator = NO;
_scrollView.scrollsToTop = NO;
_scrollView.delegate = self;
pageControl.numberOfPages = [_arrUrlLinks count];
pageControl.currentPage = 0;
// pages are created on demand
// load the visible page
// load the page on either side to avoid flashes when the user starts scrolling
[self loadScrollViewWithPage:0];
[self loadScrollViewWithPage:1];
}
- (void)loadScrollViewWithPage:(int)page {
if (page < 0) return;
if (page >= [_arrUrlLinks count])
return;
// replace the placeholder if necessary
controller1 = [viewControllers1 objectAtIndex:page];
if ((NSNull *)controller1 == [NSNull null]) {
NSString *deviceType = [UIDevice currentDevice].model;
if([deviceType isEqualToString:@"iPhone"])
{
controller1 = [[MyViewController alloc] initWithNibName:@"MyViewController" bundle:nil];
}
else{
controller1 = [[MyViewController alloc] initWithNibName:@"MyViewController_ipad" bundle:nil];
}
[controller1 initWithPageNumber:page];
[controller1 setArrData:_arrUrlLinks];
[viewControllers1 replaceObjectAtIndex:page withObject:controller1];
//[controller release];
}
// add the controller's view to the scroll view
if (nil == controller1.view.superview) {
CGRect frame = _scrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
controller1.view.frame = frame;
[_scrollView addSubview:controller1.view];
}
}
- (void)unloadScrollViewWithPage:(int)page {
if (page < 0) return;
if (page >= [_arrUrlLinks count]) return;
controller1 = [viewControllers1 objectAtIndex:page];
if ((NSNull *)controller1 != [NSNull null]) {
if (nil != controller1.view.superview)
[controller1.view removeFromSuperview];
[viewControllers1 replaceObjectAtIndex:page withObject:[NSNull null]];
// [[NSURLCache sharedURLCache] removeAllCachedResponses];
}
}
- (void)scrollViewDidScroll:(UIScrollView *)sender {
// We don't want a "feedback loop" between the UIPageControl and the scroll delegate in
// which a scroll event generated from the user hitting the page control triggers updates from
// the delegate method. We use a boolean to disable the delegate logic when the page control is used.
if (pageControlUsed) {
// do nothing - the scroll was initiated from the page control, not the user dragging
return;
}
// Switch the indicator when more than 50% of the previous/next page is visible
CGFloat pageWidth = _scrollView.frame.size.width;
int page = floor((_scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
pageControl.currentPage = page;
// NSLog(@"current page %d",page);
// load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling)
[self unloadScrollViewWithPage:page - 2];
[self loadScrollViewWithPage:page - 1];
[self loadScrollViewWithPage:page];
[self loadScrollViewWithPage:page + 1];
[self unloadScrollViewWithPage:page + 2];
count=page+1;
// [self newCountTitleSet];
// A possible optimization would be to unload the views+controllers which are no longer visible
}
// At the begin of scroll dragging, reset the boolean used when scrolls originate from the UIPageControl
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollViewLoc
{
CGFloat pageWidth = scrollViewLoc.frame.size.width;
CGPoint translation = [scrollViewLoc.panGestureRecognizer translationInView:scrollViewLoc.superview];
int page = floor((scrollViewLoc.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
if(translation.x > 0)
{
if(count!=0)
{
if(page==0)
{
[self DownLoadDataPrevious:count-1];
}
}
else{
if(page==1)
{
[btnPreviousNews setImage:[UIImage imageNamed:@"arrow2_prev.png"] forState:UIControlStateNormal];
btnPreviousNews.userInteractionEnabled=FALSE;
}
}
} else
{
btnPreviousNews.userInteractionEnabled=TRUE;
[btnPreviousNews setImage:[UIImage imageNamed:@"arrow1_prev.png"] forState:UIControlStateNormal];
if(count+1!=[_arrUrlLinks count])
{
if(page+1==[_arrUrlLinks count])
{
[self DownLoadDataNext:count+1];
}
count=count+1;
}
}
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
pageControlUsed = NO;
}
- (IBAction)changePageToNext:(id)sender {
btnPreviousNews.userInteractionEnabled=TRUE;
[btnPreviousNews setImage:[UIImage imageNamed:@"arrow1_prev.png"] forState:UIControlStateNormal];
int page = count;
// load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling)
[self loadScrollViewWithPage:page - 1];
[self loadScrollViewWithPage:page];
[self loadScrollViewWithPage:page + 1];
// update the scroll view to the appropriate page
CGRect frame = scrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
[_scrollView scrollRectToVisible:frame animated:YES];
// Set the boolean used when scrolls originate from the UIPageControl. See scrollViewDidScroll: above.
pageControlUsed = YES;
count=count+1;
// [self newCountTitleSet];
}
- (IBAction)changePageToPrev:(id)sender {
// CGFloat pageWidth = scrollView.frame.size.width;
// int page2 = floor((scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
// NSLog(@"current page %d",page2);
//
count=count-1;
NSLog(@"count %d",count);
int page = count-1;
NSLog(@"page %d",page);
if(count==0)
{
if(page==0)
{
[btnPreviousNews setImage:[UIImage imageNamed:@"arrow2_prev.png"] forState:UIControlStateNormal];
btnPreviousNews.userInteractionEnabled=FALSE;
}
if(page>=0)
{
// [self newCountTitleSet];
}
}
else{
if(page<0)
{
[self DownLoadDataPrevious:count-1];
_lblNewsCount.text=[NSString stringWithFormat:@"%d/%d",1,[_arrUrlLinks count]];
}
else{
// [self newCountTitleSet];
}
}
// load the visible page and the page on either side of it (to avoid flashes when the user starts scrolling)
[self loadScrollViewWithPage:page - 1];
[self loadScrollViewWithPage:page];
[self loadScrollViewWithPage:page + 1];
// update the scroll view to the appropriate page
CGRect frame = _scrollView.frame;
frame.origin.x = frame.size.width * page;
frame.origin.y = 0;
[_scrollView scrollRectToVisible:frame animated:YES];
// Set the boolean used when scrolls originate from the UIPageControl. See scrollViewDidScroll: above.
pageControlUsed = YES;
}
我正在使用：
NSURL *imgurl =[NSURL URLWithString:[[Dic valueForKey:@"image"] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
self._imageView1.image=[UIImage imageWithData:[NSData dataWithContentsOfURL:imgurl]];
从字典中获取图像并在滚动视图中显示它们
【问题讨论】：
-
究竟是哪一行导致了问题？
-
使用故事板，对吧？
-
不，我使用的是 xib 文件而不是故事板
-
看起来您正在尝试像字典一样使用 NSString。也许你使用了一个 id 类型的对象并且没有检查它的类。在您的代码中寻找类似
valueForKey:(NSString *)或objectForKey:(NSString *)的内容 -
不，我有一本名为 Dic 的字典，其中有一个名为“images”的键用于存储图像。
标签： ios objective-c