更新：我自己回答了这个问题;使用AVPlayer播放多个同步视频时，在UICollectionView中产生完美平滑滚动的代码...
以下代码一次最多可播放10个AVPlayers，每个AVPlayer都位于一个集合视图单元格中。它没有崩溃，播放流畅;唯一的问题，可怕的滚动：
//
// ViewController.m
// VideoWall
//
// Created by James Alan Bush on 6/13/16.
// Copyright © 2016 James Alan Bush. All rights reserved.
//
#import "ViewController.h"
#import "AppDelegate.h"
static NSString *kCellIdentifier = @"Cell Identifier";
@interface ViewController () {
dispatch_queue_t dispatchQueueLocal;
}
@end
@implementation ViewController
- (id)initWithCollectionViewLayout:(UICollectionViewFlowLayout *)layout
{
if (self = [super initWithCollectionViewLayout:layout])
{
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:kCellIdentifier];
dispatchQueueLocal = dispatch_queue_create( "local session queue", DISPATCH_QUEUE_CONCURRENT );
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
[self.collectionView setDataSource:self];
[self.collectionView setContentSize:CGSizeMake(AppDelegate.sharedAppDelegate.width, AppDelegate.sharedAppDelegate.height)];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (void)dealloc {
[super dealloc];
}
#pragma mark <UICollectionViewDataSource>
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
#pragma mark - UICollectionViewDataSource
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return AppDelegate.sharedAppDelegate.assetsFetchResults.count;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = (UICollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:kCellIdentifier forIndexPath:indexPath];
[CATransaction begin];
[CATransaction setCompletionBlock:^{
cell.contentView.layer.sublayers = nil;
dispatch_release(dispatchQueueLocal);
}];
dispatch_retain(dispatchQueueLocal);
dispatch_async( dispatchQueueLocal, ^{
[self drawPlayerLayerForCell:cell atIndexPath:indexPath];
});
[CATransaction commit];
return cell;
}
- (void)drawPlayerLayerForCell:(UICollectionViewCell *)cell atIndexPath:(NSIndexPath *)indexPath {
void (^drawPlayerLayer)(UICollectionViewCell*, NSIndexPath*) = ^(UICollectionViewCell* cell, NSIndexPath* indexPath) {
[AppDelegate.sharedAppDelegate.imageManager requestPlayerItemForVideo:AppDelegate.sharedAppDelegate.assetsFetchResults[indexPath.item] options:nil resultHandler:^(AVPlayerItem * _Nullable playerItem, NSDictionary * _Nullable info) {
dispatch_async(dispatch_get_main_queue(), ^{
if(![[info objectForKey:PHImageResultIsInCloudKey] boolValue]) {
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:[AVPlayer playerWithPlayerItem:playerItem]];
[playerLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
[playerLayer setBorderColor:[UIColor whiteColor].CGColor];
[playerLayer setBorderWidth:1.0f];
[playerLayer setFrame:cell.contentView.bounds];
[cell.contentView.layer addSublayer:playerLayer];
[(AVPlayer *)playerLayer.player play];
} else {
[AppDelegate.sharedAppDelegate.imageManager requestImageForAsset:AppDelegate.sharedAppDelegate.assetsFetchResults[indexPath.item]
targetSize:CGSizeMake(AppDelegate.sharedAppDelegate.flowLayout.itemSize.width, AppDelegate.sharedAppDelegate.flowLayout.itemSize.height)
contentMode:PHImageContentModeAspectFill
options:nil
resultHandler:^(UIImage *result, NSDictionary *info) {
dispatch_async(dispatch_get_main_queue(), ^{
cell.contentView.layer.contents = (__bridge id)result.CGImage;
});
}];
}
});
}];
};
drawPlayerLayer(cell, indexPath);
}
@end
这是另一个文件（AppDelegate.m - 是的，它只需要两个文件来执行此操作，并且没有XIB / NIB）：
//
// AppDelegate.m
// VideoWall
//
// Created by James Alan Bush on 6/13/16.
// Copyright © 2016 James Alan Bush. All rights reserved.
//
#import "AppDelegate.h"
#import "ViewController.h"
@implementation AppDelegate
+ (AppDelegate *)sharedAppDelegate
{
return (AppDelegate *)[[UIApplication sharedApplication] delegate];
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch
self.width = [[UIScreen mainScreen] bounds].size.width / 2.0;
self.height = [[UIScreen mainScreen] bounds].size.height / 4.0;
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window.rootViewController = [self viewController];
self.window.rootViewController.view = self.viewController.view;
[self.window makeKeyAndVisible];
return YES;
}
- (ViewController *)viewController {
ViewController *c = self->_viewController;
if (!c) {
c = [[ViewController alloc] initWithCollectionViewLayout:[self flowLayout]];
[c.view setFrame:[[UIScreen mainScreen] bounds]];
self->_viewController = c;
}
return c;
}
- (UICollectionViewFlowLayout *)flowLayout {
UICollectionViewFlowLayout *v = self->_flowLayout;
if (!v) {
v = [UICollectionViewFlowLayout new];
[v setItemSize:CGSizeMake(AppDelegate.sharedAppDelegate.width, AppDelegate.sharedAppDelegate.height)];
[v setSectionInset:UIEdgeInsetsMake(0.0, 0.0, 0.0, 0.0)];
[v setMinimumLineSpacing:0.0];
[v setMinimumInteritemSpacing:0.0];
[v setEstimatedItemSize:CGSizeMake(AppDelegate.sharedAppDelegate.width, AppDelegate.sharedAppDelegate.height)];
self->_flowLayout = v;
}
return v;
}
- (PHCachingImageManager *)imageManager {
PHCachingImageManager *i = self->_imageManager;
if (!i) {
i = [[PHCachingImageManager alloc] init];
self->_imageManager = i;
}
return i;
}
- (PHFetchResult *)assetsFetchResults {
PHFetchResult *i = self->_assetsFetchResults;
if (!i) {
PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumVideos options:nil];
PHAssetCollection *collection = smartAlbums.firstObject;
if (![collection isKindOfClass:[PHAssetCollection class]])
return nil;
PHFetchOptions *allPhotosOptions = [[PHFetchOptions alloc] init];
allPhotosOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
i = [PHAsset fetchAssetsInAssetCollection:collection options:allPhotosOptions];
self->_assetsFetchResults = i;
}
return i;
}
- (void)applicationWillResignActive:(UIApplication *)application {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
- (void)applicationWillTerminate:(UIApplication *)application {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
@end
任何人都知道如何解决这个问题？
ADDED：这是一个开始：NSCache，我用各种对象多次尝试过，但没有成功;这段代码缓存了整个单元格，在我看到之前我不知道你能做什么。工作完美，但需要提前查找;现在，你可以快速向后滚动，但前进是相同的......
//
// ViewController.m
// VideoWall
//
// Created by James Alan Bush on 6/13/16.
// Copyright © 2016 James Alan Bush. All rights reserved.
//
#import "ViewController.h"
#import "AppDelegate.h"
static NSString *kCellIdentifier = @"Cell Identifier";
@interface ViewController () {
//dispatch_queue_t dispatchQueueLocal;
}
@end
@implementation ViewController
- (id)initWithCollectionViewLayout:(UICollectionViewFlowLayout *)layout
{
if (self = [super initWithCollectionViewLayout:layout])
{
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:kCellIdentifier];
//dispatchQueueLocal = dispatch_queue_create( "local session queue", DISPATCH_QUEUE_CONCURRENT );
self.myCache = [[NSCache alloc] init];
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
[self.collectionView setDataSource:self];
[self.collectionView setContentSize:CGSizeMake(AppDelegate.sharedAppDelegate.width, AppDelegate.sharedAppDelegate.height)];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (void)dealloc {
[super dealloc];
}
#pragma mark <UICollectionViewDataSource>
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
#pragma mark - UICollectionViewDataSource
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return AppDelegate.sharedAppDelegate.assetsFetchResults.count;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
id cell = [self cellForIndexPathItem:[NSNumber numberWithInteger:indexPath.item]];
if (!cell) {
cell = (UICollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:kCellIdentifier forIndexPath:indexPath];
dispatch_queue_t dispatchQueueLocal = [dispatch_queue_create( "local session queue", DISPATCH_QUEUE_CONCURRENT ) autorelease];
[CATransaction begin];
[CATransaction setCompletionBlock:^{
[[(UICollectionViewCell *)cell contentView].layer.sublayers makeObjectsPerformSelector:@selector(removeFromSuperlayer)];
}];
dispatch_async( dispatchQueueLocal, ^{
[self drawPlayerLayerForCell:cell atIndexPath:indexPath];
});
[CATransaction commit];
[self performSelector:@selector(setCell:forIndexPathItem:) withObject:cell withObject:[NSNumber numberWithInteger:indexPath.item]];
}
return cell;
}
- (void)drawPlayerLayerForCell:(UICollectionViewCell *)cell atIndexPath:(NSIndexPath *)indexPath {
void (^drawPlayerLayer)(UICollectionViewCell*, NSIndexPath*) = ^(UICollectionViewCell* cell, NSIndexPath* indexPath) {
[AppDelegate.sharedAppDelegate.imageManager requestPlayerItemForVideo:AppDelegate.sharedAppDelegate.assetsFetchResults[indexPath.item] options:nil resultHandler:^(AVPlayerItem * _Nullable playerItem, NSDictionary * _Nullable info) {
dispatch_async(dispatch_get_main_queue(), ^{
if(![[info objectForKey:PHImageResultIsInCloudKey] boolValue]) {
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:[AVPlayer playerWithPlayerItem:playerItem]];
[playerLayer setVideoGravity:AVLayerVideoGravityResizeAspect];
[playerLayer setBorderColor:[UIColor darkGrayColor].CGColor];
[playerLayer setBorderWidth:0.5f];
[playerLayer setFrame:cell.contentView.bounds];
[cell.contentView.layer addSublayer:playerLayer];
[(AVPlayer *)playerLayer.player play];
} else {
[AppDelegate.sharedAppDelegate.imageManager requestImageForAsset:AppDelegate.sharedAppDelegate.assetsFetchResults[indexPath.item]
targetSize:CGSizeMake(AppDelegate.sharedAppDelegate.flowLayout.itemSize.width, AppDelegate.sharedAppDelegate.flowLayout.itemSize.height)
contentMode:PHImageContentModeAspectFill
options:nil
resultHandler:^(UIImage *result, NSDictionary *info) {
dispatch_async(dispatch_get_main_queue(), ^{
cell.contentView.layer.contents = (__bridge id)result.CGImage;
});
}];
}
});
}];
};
drawPlayerLayer(cell, indexPath);
}
- (id)cellForIndexPathItem:(NSNumber *)number {
return [self.myCache objectForKey:number];
}
- (void)setCell:(id)cell forIndexPathItem:(NSNumber *)number {
[self.myCache setObject:cell forKey:number];
}
@end
---更新---
在UICollectionViewController.m中：
//
// CollectionViewController.m
// ChromaEpsilonZeta
//
// Created by James Alan Bush on 6/27/16.
// Copyright © 2016 James Alan Bush. All rights reserved.
//
#import "CollectionViewController.h"
#import "CollectionViewCell.h"
#import "AppDelegate.h"
@interface CollectionViewController ()
@end
@implementation CollectionViewController
static NSString * const reuseIdentifier = @"Cell";
- (void)viewDidLoad {
[super viewDidLoad];
[self.collectionView registerClass:[CollectionViewCell class] forCellWithReuseIdentifier:reuseIdentifier];
}
- (void)awakeFromNib
{
[super awakeFromNib];
NSLog(@"awakeFromNib");
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
for (NSInteger i = 0; i < AppDelegate.sharedAppDelegate.assetsFetchResults.count; i++) {
[self createCellForIndexPath:[NSIndexPath indexPathForItem:i inSection:0]];
NSLog(@"Adding cell %ld out of %ld", i + 1, AppDelegate.sharedAppDelegate.assetsFetchResults.count);
}
});
}
- (CollectionViewCell *)createCellForIndexPath:(NSIndexPath *)indexPath {
[AppDelegate.sharedAppDelegate.mappedCells setObject:[self.collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath] forKey:indexPath];
return (CollectionViewCell *)[AppDelegate.sharedAppDelegate.mappedCells objectForKey:indexPath];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
#pragma mark <UICollectionViewDataSource>
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return AppDelegate.sharedAppDelegate.assetsFetchResults.count;
}
- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
[(CollectionViewCell *)[AppDelegate.sharedAppDelegate.mappedCells objectForKey:indexPath] setIndexPath:indexPath];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.item < 0) indexPath = [NSIndexPath indexPathForItem:0 inSection:0];
NSLog(@"Cell %ld", indexPath.item);
[(CollectionViewCell *)[AppDelegate.sharedAppDelegate.mappedCells objectForKey:indexPath] playVideo];
return (CollectionViewCell *)[AppDelegate.sharedAppDelegate.mappedCells objectForKey:indexPath];
}
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
[(CollectionViewCell *)[AppDelegate.sharedAppDelegate.mappedCells objectForKey:indexPath] stopVideo];
[self createCellForIndexPath:indexPath];
}
在AppDelegate .m文件中：
+ (AppDelegate *)sharedAppDelegate
{
return (AppDelegate *)[[UIApplication sharedApplication] delegate];
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
return YES;
}
- (CollectionViewController *)collectionViewController {
CollectionViewController *c = self->_collectionViewController;
if (!c) {
c = [[CollectionViewController alloc] initWithCollectionViewLayout:[self flowLayout]];
[c.view setFrame:[[UIScreen mainScreen] bounds]];
self->_collectionViewController = c;
}
return c;
}
- (UICollectionViewFlowLayout *)flowLayout {
UICollectionViewFlowLayout *v = self->_flowLayout;
if (!v) {
v = [[UICollectionViewFlowLayout alloc] init];
[v setItemSize:CGSizeMake(360.0, 240.0)];
[v setSectionInset:UIEdgeInsetsMake(0.0, 0.0, 0.0, 0.0)];
[v setMinimumLineSpacing:0.0];
[v setMinimumInteritemSpacing:0.0];
[v setEstimatedItemSize:CGSizeMake(227.0, 128.0)];
[v setScrollDirection:UICollectionViewScrollDirectionHorizontal];
self->_flowLayout = v;
}
return v;
}
- (PHCachingImageManager *)imageManager {
PHCachingImageManager *i = self->_imageManager;
if (!i) {
i = [[PHCachingImageManager alloc] init];
self->_imageManager = i;
}
return i;
}
- (PHFetchResult *)assetsFetchResults {
PHFetchResult *i = self->_assetsFetchResults;
if (!i) {
PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumVideos options:nil];
PHAssetCollection *collection = smartAlbums.firstObject;
if (![collection isKindOfClass:[PHAssetCollection class]])
return nil;
PHFetchOptions *allPhotosOptions = [[PHFetchOptions alloc] init];
allPhotosOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
i = [PHAsset fetchAssetsInAssetCollection:collection options:allPhotosOptions];
self->_assetsFetchResults = i;
}
return i;
}
- (NSMapTable *)mappedCells {
NSMapTable *m = self->_mappedCells;
if (!m) {
m = [[NSMapTable alloc] initWithKeyOptions:NSMapTableStrongMemory valueOptions:NSMapTableStrongMemory capacity:self.assetsFetchResults.count];
self->_mappedCells = m;
NSLog(@"NSMapTable created");
}
NSLog(@"NSMapTable object count: %ld", m.count);
return m;
}
在UICollectionViewCell子类（.m）文件中：
- (id)initWithFrame:(CGRect)frame
{
if (!(self = [super initWithFrame:frame])) return nil;
self.backgroundColor = [UIColor blackColor];
return self;
}
- (void)playVideo {
self.player = [AVPlayer playerWithPlayerItem:self.playerItem];
self.playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player];
[self.playerLayer setFrame:self.contentView.layer.bounds];
[self.playerLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
[self.playerLayer setBorderColor:[UIColor whiteColor].CGColor];
[self.playerLayer setBorderWidth:0.25f];
[self.contentView.layer addSublayer:self.playerLayer];
[(AVPlayer *)self.player play];
NSLog(@"play");
}
- (void)stopVideo {
[(AVPlayer *)self.player pause];
self.contentView.layer.sublayers = nil;
NSLog(@"stop");
}
- (void)setIndexPath:(NSIndexPath *)indexPath {
self->_indexPath = [NSIndexPath indexPathForItem:indexPath.item inSection:0];
PHVideoRequestOptions *videoOptions = [[PHVideoRequestOptions alloc] init];
videoOptions.version = PHVideoRequestOptionsVersionCurrent;
videoOptions.deliveryMode = PHVideoRequestOptionsDeliveryModeFastFormat;
[[PHImageManager defaultManager] requestPlayerItemForVideo:AppDelegate.sharedAppDelegate.assetsFetchResults[self->_indexPath.item] options:videoOptions resultHandler:^(AVPlayerItem * _Nullable playerItem, NSDictionary * _Nullable info) {
if(![[info objectForKey:PHImageResultIsInCloudKey] boolValue]) {
dispatch_async(dispatch_get_main_queue(), ^{
self.playerItem = playerItem;
});
} else {
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
options.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;
options.resizeMode = PHImageRequestOptionsResizeModeExact;
//if (self.contentView.layer.sublayers.count > 0) self.contentView.layer.sublayers = nil;
[[PHImageManager defaultManager] requestImageForAsset:AppDelegate.sharedAppDelegate.assetsFetchResults[self->_indexPath.item]
targetSize:self.contentView.layer.bounds.size
contentMode:PHImageContentModeAspectFill
options:options
resultHandler:^(UIImage *result, NSDictionary *info) {
dispatch_async(dispatch_get_main_queue(), ^{
self.contentView.layer.contents = (__bridge id)result.CGImage;
});
}];
}
}];
}
欢迎你。