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。