在 UIScrollView 上添加 UIImageView，同时在 UITapGestureRecognizer 上添加 UIImageView

Question

我有 UIViewController ，上面有 UIScrollView 。 UIScrollView有各种平铺图像，如Apple Developer平铺图像层程序。我正在尝试使用 UITapGestureRecognizer 来了解位置并在其顶部放置一个带有 uiimage 的 uiimageview 。但不知何故它永远不会放置图像文件。

- (void)loadView 
{    
CGRect pagingScrollViewFrame = [self frameForPagingScrollView];
pagingScrollView = [[UIScrollView alloc] initWithFrame:pagingScrollViewFrame];
pagingScrollView.pagingEnabled = YES;
pagingScrollView.backgroundColor = [UIColor clearColor];
pagingScrollView.showsVerticalScrollIndicator = NO;
pagingScrollView.showsHorizontalScrollIndicator = NO;
pagingScrollView.userInteractionEnabled = YES;
pagingScrollView.contentSize = [self contentSizeForPagingScrollView];
pagingScrollView.delegate = self;
self.view = pagingScrollView;


UIGestureRecognizer *recognizer;

recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapFrom:)];
[pagingScrollView addGestureRecognizer:recognizer];
self.tapRecognizer = (UITapGestureRecognizer *)recognizer;
recognizer.delegate = self;
[recognizer release];

recycledPages = [[NSMutableSet alloc] init];
visiblePages  = [[NSMutableSet alloc] init];
[self tilePages];

[pagingScrollView addSubview:imageView]; /// **** Here I am Adding to ScrollView *****//

}

- (void)showImageWithText:(NSString *)string atPoint:(CGPoint)centerPoint {

imageView.image = [UIImage imageNamed:@"image.png"];
imageView.center = centerPoint;
imageView.alpha = 1.0;  
 }


- (void)handleTapFrom:(UITapGestureRecognizer *)recognizer {

CGPoint location = [recognizer locationInView:pagingScrollView];

int tapX = (int) location.x;
    int tapY = (int) location.y;
    [self showImageWithText:@"tap" atPoint:location];

   }

  //****More Code  Same code like TilingLayer.m from Apple Developer Kit ****//
- (void)tilePages 
 {
  // Calculate which pages are visible
CGRect visibleBounds = pagingScrollView.bounds;
int firstNeededPageIndex = floorf(CGRectGetMinX(visibleBounds) / CGRectGetWidth(visibleBounds));
int lastNeededPageIndex  = floorf((CGRectGetMaxX(visibleBounds)-1) / CGRectGetWidth(visibleBounds));
firstNeededPageIndex = MAX(firstNeededPageIndex, 0);
lastNeededPageIndex  = MIN(lastNeededPageIndex, [self imageCount] - 1);

// Recycle no-longer-visible pages 
for (ImageScrollView *page in visiblePages) {
    if (page.index < firstNeededPageIndex || page.index > lastNeededPageIndex) {
        [recycledPages addObject:page];
        [page removeFromSuperview];
    }
}
[visiblePages minusSet:recycledPages];

// add missing pages
for (int index = firstNeededPageIndex; index <= lastNeededPageIndex; index++) {
    if (![self isDisplayingPageForIndex:index]) {
        ImageScrollView *page = [self dequeueRecycledPage];
        if (page == nil) {
            page = [[[ImageScrollView alloc] init] autorelease];
        }
        [self configurePage:page forIndex:index];
        [pagingScrollView addSubview:page];
        [visiblePages addObject:page];
    }
}    

。

我不确定我在这里做错了什么 如果有人遇到过这样的问题可以与我分享想法。

Answer 1

我可能错过了一些东西，但你的 imageView 为零。

您添加 [pagingScrollView addSubview:imageView] 但此时 imageView 尚未实例化。

由于您总是分配相同的图像，因此您应该这样做：

imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image.png"]];

在“loadView”内部和

[imageView release];
imageView = nil;

“viewDidUnload”内部