我目前正在尝试像照片应用程序一样实现照片选择器，但使用自定义图像源。 对于“照片滚动”部分，我使用了Apple PhotoScroller示例代码并对其进行了调整。其中一个主要区别在于它现在嵌入了一个导航控制器（哪个是photoPicker自己的导航控制器，而不是应用程序的导航控制器），带有导航栏。 我的状态和导航栏是半透明的，我在photoPicker中使用的所有视图控制器上设置了wantFullScreenLayout = YES。它似乎工作得很好。 “概览”视图（显示所有相册照片缩略图的视图）确实是全屏的，我必须手动偏移它，以便首先在导航栏下显示缩略图。 然而，对于滚动部分，存在一个小故障。 对于那些不知道photoScroller示例代码的人来说，它适用于带有UIScrollView属性（pagingScrollView）的自定义UIViewController（PhotoViewController），以及带有UIView和NSInteger索引属性的一组自定义UIScrollView（ImageScrollView）。然后添加/删除ImageScrollView实例作为PhotoScroller的子视图。
以下是一些相关代码：
PhotoViewController.h
@interface PhotoViewController : UIViewController <UIScrollViewDelegate> {
UIScrollView *pagingScrollView;
NSMutableSet *recycledPages;
NSMutableSet *visiblePages;
IBOutlet UIToolbar *toolbar;
IBOutlet UIBarButtonItem *previousButtonItem;
IBOutlet UIBarButtonItem *nextButtonItem;
id<PhotoViewDataSource> dataSource;
}
@property(nonatomic, retain) UIScrollView *pagingScrollView;
@property(nonatomic, retain) NSMutableSet *recylcledPages;
@property(nonatomic, retain) NSMutableSet *visiblePages;
@property(nonatomic, retain) UIToolbar *toolbar;
@property(nonatomic, retain) UIBarButtonItem *previousButtonItem;
@property(nonatomic, retain) UIBarButtonItem *nextButtonItem;
@property(nonatomic, retain) id<PhotoViewDataSource> dataSource;
PhotoViewController.m
- (void)loadView
{
self.wantsFullScreenLayout = YES;
// Configure the scrollView
CGRect pagingScrollViewFrame = [self frameForPagingScrollView];
pagingScrollView = [[UIScrollView alloc] initWithFrame:pagingScrollViewFrame];
pagingScrollView.pagingEnabled = YES;
pagingScrollView.backgroundColor = [UIColor redColor];
pagingScrollView.showsVerticalScrollIndicator = NO;
pagingScrollView.showsHorizontalScrollIndicator = NO;
pagingScrollView.contentSize = CGSizeMake(pagingScrollViewFrame.size.width * [self.dataSource imageCount],
pagingScrollViewFrame.size.height);
//pagingScrollView.contentOffset = CGPointMake(0, 0);
pagingScrollView.delegate = self;
self.view = pagingScrollView;
// TODO ? Prepare to tile content
recycledPages = [[NSMutableSet alloc] init];
visiblePages = [[NSMutableSet alloc] init];
[self processPages];
}
- (void)processPages {
// Calculate which pages are visible
CGRect visibleBounds = pagingScrollView.bounds;
NSLog(@"PhotoViewController - processPages : frame = %@", NSStringFromCGRect(pagingScrollView.frame));
NSLog(@"pagingScrollView bounds = %@", NSStringFromCGRect(pagingScrollView.bounds));
NSLog(@"and contentSize = %@", NSStringFromCGSize(pagingScrollView.contentSize));
int firstNeededPageIndex = floorf(CGRectGetMinX(visibleBounds) / CGRectGetWidth(visibleBounds));
int lastNeededPageIndex = floorf((CGRectGetMaxX(visibleBounds)-1) / CGRectGetWidth(visibleBounds));
firstNeededPageIndex = MAX(firstNeededPageIndex, 0);
lastNeededPageIndex = MIN(lastNeededPageIndex, [dataSource imageCount] - 1);
if (lastNeededPageIndex >= 0) {
// 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];
NSLog(@"PhotoViewController - processPage 2 : bounds = %@", NSStringFromCGRect(pagingScrollView.bounds));
[pagingScrollView addSubview:page];
NSLog(@"PhotoViewController - processPage 3 : bounds = %@", NSStringFromCGRect(pagingScrollView.bounds));
[visiblePages addObject:page];
}
}
}
}
- (ImageScrollView *)dequeueRecycledPage {
ImageScrollView *page = [recycledPages anyObject];
if (page) {
[[page retain] autorelease];
[recycledPages removeObject:page];
}
return page;
}
- (BOOL)isDisplayingPageForIndex:(NSUInteger)index {
BOOL foundPage = NO;
for (ImageScrollView *page in visiblePages) {
if (page.index == index) {
foundPage = YES;
break;
}
}
return foundPage;
}
- (void)configurePage:(ImageScrollView *)page forIndex:(NSUInteger)index {
page.index = index;
page.frame = [self frameForPageAtIndex:index];
NSLog(@"PhotoViewController - configurePage : bounds = %@", NSStringFromCGRect(pagingScrollView.bounds));
[page displayImage:[dataSource imageForImageId:index]];
NSLog(@"PhotoViewController - configurePage 2 : bounds = %@", NSStringFromCGRect(pagingScrollView.bounds));
}
#pragma mark -
#pragma mark ScrollView delegate methods
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
[self processPages];
}
#pragma mark -
#pragma mark Frame calculations
#define PADDING 10
- (CGRect)frameForPagingScrollView {
CGRect frame = [[UIScreen mainScreen] bounds];
frame.origin.x -= PADDING;
frame.size.width += (2*PADDING);
return frame;
}
- (CGRect)frameForPageAtIndex:(NSUInteger)index {
CGRect pagingScrollViewFrame = [self frameForPagingScrollView];
CGRect pageFrame = pagingScrollViewFrame;
pageFrame.size.width -= (2 * PADDING);
pageFrame.origin.x = (pagingScrollViewFrame.size.width * index) + PADDING;
//pageFrame.origin.x = (pagingScrollViewFrame.size.width * index) - (PADDING*index*2);
return pageFrame;
}
ImageScrollView.h
@interface ImageScrollView : UIScrollView <UIScrollViewDelegate> {
UIView *imageView;
NSUInteger index;
}
@property (assign) NSUInteger index;
- (void)displayImage:(UIImage *)image;
//- (void)displayTiledImageNamed:(NSString *)imageName size:(CGSize)imageSize;
- (void)configureForImageSize:(CGSize)imageSize;
ImageScrollView.m
- (void)layoutSubviews
{
[super layoutSubviews];
imageView.backgroundColor = [UIColor greenColor];
self.backgroundColor = [UIColor blueColor];
// center the image as it becomes smaller than the size of the screen
CGSize boundsSize = self.bounds.size;
CGRect frameToCenter = imageView.frame;
// center horizontally
if (frameToCenter.size.width < boundsSize.width)
frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2;
else
frameToCenter.origin.x = 0;
// center vertically
if (frameToCenter.size.height < boundsSize.height)
frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2;
else
frameToCenter.origin.y = 0;
imageView.frame = frameToCenter;
NSLog(@"imageView frame = %@", NSStringFromCGRect(frameToCenter));
if ([imageView isKindOfClass:[TilingView class]]) {
// to handle the interaction between CATiledLayer and high resolution screens, we need to manually set the
// tiling view's contentScaleFactor to 1.0. (If we omitted this, it would be 2.0 on high resolution screens,
// which would cause the CATiledLayer to ask us for tiles of the wrong scales.)
imageView.contentScaleFactor = 1.0;
}
}
#pragma mark -
#pragma mark UIScrollView delegate methods
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return imageView;
}
#pragma mark -
#pragma mark Configure scrollView to display new image (tiled or not)
- (void)displayImage:(UIImage *)image
{
// clear the previous imageView
[imageView removeFromSuperview];
[imageView release];
imageView = nil;
// reset our zoomScale to 1.0 before doing any further calculations
self.zoomScale = 1.0;
// make a new UIImageView for the new image
imageView = [[UIImageView alloc] initWithImage:image];
[self addSubview:imageView];
[self configureForImageSize:[image size]];
}
- (void)configureForImageSize:(CGSize)imageSize
{
CGSize boundsSize = [self bounds].size;
// set up our content size and min/max zoomscale
CGFloat xScale = boundsSize.width / imageSize.width; // the scale needed to perfectly fit the image width-wise
CGFloat yScale = boundsSize.height / imageSize.height; // the scale needed to perfectly fit the image height-wise
CGFloat minScale = MIN(xScale, yScale); // use minimum of these to allow the image to become fully visible
// on high resolution screens we have double the pixel density, so we will be seeing every pixel if we limit the
// maximum zoom scale to 0.5.
CGFloat maxScale = /*1.0 / */[[UIScreen mainScreen] scale];
// don't let minScale exceed maxScale. (If the image is smaller than the screen, we don't want to force it to be zoomed.)
if (minScale > maxScale) {
minScale = maxScale;
}
self.contentSize = imageSize;
self.maximumZoomScale = maxScale;
self.minimumZoomScale = minScale;
self.zoomScale = minScale; // start out with the content fully visible
}
我的问题是，当我第一次加载PhotoViewController实例时，pagingScrollView正在偏移到（0，-64）像素的原点（状态栏的高度+我认为的导航栏）。这导致了一个混乱的界面，其中ImageScrollView出现在导航栏（origin（0,0））下方，然后即使其高度小于屏幕也可以上下滚动。
通过一些日志和断点，我能够确定在加载过程开始时pagingScrollView边界是正常的。当我缩放ImageScrollView的图像以适应屏幕时，它们会发生变化。这会导致viewForZoomingInScrollView，然后调用scrollViewDidScroll方法。在这些调用期间，pagingScrollView正在被偏移。
我尝试手动设置偏移但是当我在processPages中执行时，scrollView无法再上下跳动...
任何帮助将不胜感激！
干杯
PB
答案 0 :(得分：6)
在您的特定情况下（即PhotoViewController被推送到UINavigationController堆栈） - 导航栏会添加contentInset到PhotoViewController的滚动视图。这更好地解释了here和here。
也就是说，PhotoViewController视图不适合您的窗口边界，因此可以在所有方向上滚动。
我找到了两个可能解决问题的方法。
1 - 您需要手动调整contentInset的{{1}}以补偿导航栏和状态栏的高度。将其添加到pagingScrollView：
PhotoViewController或
2 - 由于只有滚动视图包含- (void)viewDidLoad {
[super viewDidLoad];
CGFloat topOffset = self.navigationController.navigationBar.frame.size.height + [[UIApplication sharedApplication] statusBarFrame].size.height;
pagingScrollView.contentInset = UIEdgeInsetsMake(-topOffset, 0.0, 0.0, 0.0);
}
，因此请将contentInset包裹在普通pagingScrollView中：
UIView希望这有帮助！
答案 1 :(得分：0)
需要设置的主要内容是视图控制器中的以下内容。在内容视图上使用autoresize标志。启用以下标志会将视图控制器的大小扩展到屏幕的完整大小。我在viewWillAppear中执行以下操作。
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[self setWantsFullScreenLayout:YES]; // if you want to underlap status
self.navigationController.navigationBar.translucent = YES; // underlap nav controller
self.toolbar.translucent = YES; // if you have a toolbar.
}
更多细节可以在Apple的文档中找到：
如果你一直在做内容视图上设置框架边界的事情，我会删除所有代码，因为上面应该为你处理它。
答案 2 :(得分：0)
只需将故事板中的视图控制器的“调整滚动视图”插图设置为false即可。
答案 3 :(得分：-2)
Three20有一个非常好的实现。如果您需要任何精美的功能，它只会根据您自己的需要调整代码。
所有艰苦的工作已经完成。虽然如果你仍然想要实现自己的版本，至少要看看Three20代码并检查它们是如何实现你想要实现的。
它的样子：http://farm4.static.flickr.com/3432/3378117315_3bf905bdb6_o.jpg
