ios – 重用UICollectionView中的单元格时,会短暂显示重用的UICollectionViewCell的旧内容

概述我正在使用UICollectionView来显示从URL异步加载的图片网格.我的集合视图使用可重用单元格来显示UICollectionViewCells.当不重复使用单元格时,所有内容都会正确显示,但是当我滚动一下时,重用的单元格会在它们开始正常行为之前短暂闪烁旧内容. 以下是自定义UICollectionViewController的实现： #import "MyCollectionViewVi 我正在使用UICollectionVIEw来显示从URL异步加载的图片网格.我的集合视图使用可重用单元格来显示UICollectionVIEwCells.当不重复使用单元格时,所有内容都会正确显示,但是当我滚动一下时,重用的单元格会在它们开始正常行为之前短暂闪烁旧内容.

以下是自定义UICollectionVIEwController的实现：

#import "MyCollectionVIEwVIEwController.h"#import "MyCollectionVIEwCell.h"@interface MyCollectionVIEwVIEwController ()    @property (strong,nonatomic) NSArray *data;    @end@implementation MyCollectionVIEwVIEwController@synthesize data = _data;- (voID)vIEwDIDLoad{    [super vIEwDIDLoad];    self.data = @[        @"http://s3-ec.buzzfed.com/static/enhanced/webdr01/2013/1/18/12/enhanced-buzz-wIDe-851-1358529670-4.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr03/2013/1/18/11/enhanced-buzz-wIDe-26311-1358526816-5.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr03/2013/1/18/11/enhanced-buzz-wIDe-26311-1358527190-11.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr02/2013/1/18/11/enhanced-buzz-wIDe-7517-1358526694-11.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr03/2013/1/18/11/enhanced-buzz-wIDe-1965-1358527802-7.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr03/2013/1/18/11/enhanced-buzz-wIDe-2165-1358527708-14.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr03/2013/1/18/11/enhanced-buzz-wIDe-1965-1358527894-12.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr02/2013/1/18/12/enhanced-buzz-wIDe-15957-1358529198-18.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr02/2013/1/18/12/enhanced-buzz-wIDe-16520-1358528981-9.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr02/2013/1/18/12/enhanced-buzz-wIDe-16517-1358529292-5.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr01/2013/1/18/12/enhanced-buzz-wIDe-20349-1358529323-20.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr01/2013/1/18/12/enhanced-buzz-wIDe-32444-1358529959-9.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr01/2013/1/18/12/enhanced-buzz-wIDe-32343-1358530043-7.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr02/2013/1/18/12/enhanced-buzz-wIDe-23646-1358530321-2.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr01/2013/1/18/12/enhanced-buzz-wIDe-28223-1358530801-15.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr01/2013/1/18/12/enhanced-buzz-wIDe-32273-1358530695-16.jpg",@"http://s3-ec.buzzfed.com/static/enhanced/webdr01/2013/1/18/12/enhanced-buzz-wIDe-31288-1358531103-16.jpg"    ];    [self.collectionVIEw registerNib:[UINib nibWithNibname:@"MyCollectionVIEwCell" bundle:[NSBundle mainBundle]] forCellWithReuseIDentifIEr:@"myVIEw"];}- (UICollectionVIEwCell *)collectionVIEw:(UICollectionVIEw *)collectionVIEw cellForItemAtIndexPath:(NSIndexPath *)indexPath {    Nsstring *urlString = [self.data objectAtIndex:indexPath.item];    MyCollectionVIEwCell *myVIEw = [collectionVIEw dequeueReusableCellWithReuseIDentifIEr:@"myVIEw" forIndexPath:indexPath];    myVIEw.urlString = urlString;    [myVIEw setNeedsdisplay];    return myVIEw;}- (CGSize)collectionVIEw:(UICollectionVIEw *)collectionVIEw layout:(UICollectionVIEwLayout *)collectionVIEwLayout sizeforItemAtIndexPath:(NSIndexPath *)indexPath {    return CGSizeMake(150,150);}- (NSInteger)numberOfSectionsInCollectionVIEw:(UICollectionVIEw *)collectionVIEw {    return 1;}- (NSInteger)collectionVIEw:(UICollectionVIEw *)collectionVIEw numberOfItemsInSection:(NSInteger)section {    return self.data.count;}@end

这是自定义UICollectionVIEwCell的实现.

#import "MyCollectionVIEwCell.h"#import <QuartzCore/QuartzCore.h>#import <AVFoundation/AVFoundation.h>@interface MyCollectionVIEwCell ()@property (weak,nonatomic) IBOutlet UIImageVIEw *imageVIEw;@end@implementation MyCollectionVIEwCell@synthesize urlString = _urlString;+ (voID)loadAsyncImageFromURL:(Nsstring *)urlString withCallback:(voID (^)(UIImage *))callback {    NSURL *url = [NSURL URLWithString:urlString];    dispatch_queue_t downloadQueue = dispatch_queue_create("com.example.downloadqueue",NulL);    dispatch_async(downloadQueue,^{        NSData * imageData = [NSData dataWithContentsOfURL:url];        UIImage *image = [UIImage imageWithData:imageData];        dispatch_async(dispatch_get_main_queue(),^{            callback(image);        });    });}-(voID) fadeInVIEw:(UIVIEw *)vIEw WithSecondDuration:(double)duration {    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"opacity"];    animation.beginTime = 0;    animation.duration = duration;    animation.fromValue = [NSNumber numberWithfloat:0.0f];    animation.tovalue = [NSNumber numberWithfloat:1.0f];    animation.removedOnCompletion = NO;    animation.fillMode = kCAFillModeBoth;    animation.additive = NO;    [vIEw.layer addAnimation:animation forKey:@"opacityIN"];}- (voID) setUrlString:(Nsstring *)urlString {    _urlString = urlString;    self.imageVIEw.image = nil;    self.imageVIEw.layer.opacity = 0;    if (urlString) {        [MyCollectionVIEwCell loadAsyncImageFromURL:urlString withCallback:^(UIImage *image) {            self.imageVIEw.image = image;            [self fadeInVIEw:self.imageVIEw WithSecondDuration:.25];        }];    }}@end

解决方法 您可以尝试在单元格完成显示时将单元格的URL设置为nil,它可以在我的项目中工作.

-(voID)collectionVIEw:(UICollectionVIEw *)cv dIDEnddisplayingCell:(UICollectionVIEwCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath{    [(MyCollectionVIEwCell *)cell setUrlString:nil];}

我希望这有帮助！

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