ios获取所有相册的视频并播放

端午节前，把公司的项目忙完了，这几天开始继续DDPlayer的开发，熟悉代码之后，首先要解决的是：获取并播放相册里面的视频。
对于相册中的视频，我需要关注视频的名称、时常、格式、缩略图等信息，因此，定义了表示视频信息的对象。

//AlbumVideoInfo.h#import <Foundation/Foundation.h>#import <UIKit/UIKit.h>@interface AlbumVideoInfo : NSObject@property(nonatomic, copy) NSString *name;@property(nonatomic, assign) long long size; //Bytes@property(nonatomic, strong) NSNumber *duration;@property(nonatomic, copy) NSString *format;@property(nonatomic, strong) UIImage *thumbnail;@property (nonatomic, strong) NSURL *videoURL;@end//AlbumVideoInfo.m#import "AlbumVideoInfo.h"@implementation AlbumVideoInfo@end

然后，从相册load视频信息，并保存在数组中，相关关键函数有：

//加载视频- (void)loadVideos{    ALAssetsLibrary *library1 = [[ALAssetsLibrary alloc] init];    [library1 enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {        if (group) {            [group setAssetsFilter:[ALAssetsFilter allVideos]];            [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {                if (result) {                    AlbumVideoInfo *videoInfo = [[AlbumVideoInfo alloc] init];                    videoInfo.thumbnail = [UIImage imageWithCGImage:result.thumbnail];//                    videoInfo.videoURL = [result valueForProperty:ALAssetPropertyAssetURL];                    videoInfo.videoURL = result.defaultRepresentation.url;                    videoInfo.duration = [result valueForProperty:ALAssetPropertyDuration];                    videoInfo.name = [self getFormatedDateStringOfDate:[result valueForProperty:ALAssetPropertyDate]];                    videoInfo.size = result.defaultRepresentation.size; //Bytes                    videoInfo.format = [result.defaultRepresentation.filename pathExtension];                    [_albumVideoInfos addObject:videoInfo];                }            }];        } else {            //没有更多的group时，即可认为已经加载完成。             NSLog(@"after load, the total alumvideo count is %ld",_albumVideoInfos.count);            dispatch_async(dispatch_get_main_queue(), ^{                [self showAlbumVideos];            });        }    } failureBlock:^(NSError *error) {        NSLog(@"Failed.");    }];}

//将创建日期作为文件名-(NSString*)getFormatedDateStringOfDate:(NSDate*)date{    NSDateFormatter* dateFormatter = [[NSDateFormatter alloc] init];    [dateFormatter setTimeZone:[NSTimeZone localTimeZone]];    [dateFormatter setDateFormat:@"yyyyMMddHHmmss"]; //注意时间的格式：MM表示月份，mm表示分钟，HH用24小时制，小hh是12小时制。    NSString* dateString = [dateFormatter stringFromDate:date];    return dateString;}

最后，就是播放视频，由于相册视频不能获取到绝对地址，而KxMovieViewController初始化的参数只能是NSString类型的path（本地、远程都可以），我尝试使用相册视频url的absulutstring来初始化它，没有成功，故改为使用系统自带的MPMoviePlayerController。相关关键代码如下：

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        // Custom initialization        _albumVideoInfos = [[NSMutableArray alloc] initWithCapacity:50];        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playDidChangeNotification:) name:MPMoviePlayerPlaybackStateDidChangeNotification object:nil];        [[NSNotificationCenter defaultCenter] addObserver:self                                                 selector:@selector(playMovieFinishedCallback:)                                                     name:MPMoviePlayerPlaybackDidFinishNotification                                                   object:nil];        //MPMoviePlayerController fullscreen 模式下，点击左上角的done按钮，会调用exitFullScreen通知。        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(exitFullScreen:) name: MPMoviePlayerDidExitFullscreenNotification object:nil];    }    return self;}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{    NSInteger row = indexPath.row;    if (row < _albumVideoInfos.count) {        AlbumVideoInfo *albumVideoInfo = _albumVideoInfos[row];        if (!_moviePlayer) {            _moviePlayer = [[MPMoviePlayerController alloc] initWithContentURL:albumVideoInfo.videoURL];        }else{            [_moviePlayer setContentURL:albumVideoInfo.videoURL];        }        _moviePlayer.view.frame = self.view.bounds;        _moviePlayer.backgroundView.backgroundColor = [UIColor orangeColor];        [self.view addSubview:_moviePlayer.view];        _moviePlayer.controlStyle = MPMovieControlStyleFullscreen;        _moviePlayer.shouldAutoplay = YES;        _moviePlayer.repeatMode = MPMovieRepeatModeOne;        [_moviePlayer setFullscreen:YES animated:YES];        _moviePlayer.scalingMode = MPMovieScalingModeAspectFit;        [_moviePlayer play];    }}

相关通知的处理：

#pragma mark - handle notification- (void)playDidChangeNotification:(NSNotification *)notification {    MPMoviePlayerController *moviePlayer = notification.object;    MPMoviePlaybackState playState = moviePlayer.playbackState;    if (playState == MPMoviePlaybackStateStopped) {        NSLog(@"停止");    } else if(playState == MPMoviePlaybackStatePlaying) {        NSLog(@"播放");    } else if(playState == MPMoviePlaybackStatePaused) {        NSLog(@"暂停");    }}- (void)playMovieFinishedCallback:(NSNotification *)notification{    NSLog(@"finish");}- (void)exitFullScreen:(NSNotification *)notification{    NSLog(@"exitFullScreen");    [_moviePlayer stop];    [_moviePlayer.view removeFromSuperview];}

OK,重要的事情都说完了，but，在强调一下一个小细节。
//MPMoviePlayerController fullscreen 模式下，点击左上角的done按钮，会调用exitFullScreen通知。