iOS 截取视频的封面图或任意时间的截图

由于是通过AVAsset来处理的，所以我们要导入

#import <AVFoundation/AVFoundation.h>

/// 根据视频url对指定时间的视频截图
/// @param videoUrlStr 视频url
/// @param seconds 时间 如果是封面图传0，即取0秒的视频位置
+ (void)getVideoThumbImageWithUrlStr:(NSString *)videoUrlStr seconds:(NSTimeInterval)seconds handle:(void(^)(UIImage *thumbImage,NSError *error))handle;

/// 根据视频url对指定时间的视频截图
+ (void)getVideoThumbImageWithUrlStr:(NSString *)videoUrlStr seconds:(NSTimeInterval)seconds handle:(void(^)(UIImage *thumbImage,NSError *error))handle{
    //由于是获取线上的视频封面图，这里需要异步处理，防止阻塞主线程
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        //根据url创建asset
        AVURLAsset *asset = [[AVURLAsset alloc]initWithURL:[NSURL URLWithString:videoUrlStr] options:nil];
        //创建集合的轨道
        AVAssetTrack *track = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject;
        //创建AVAssetImageGenerator
        AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
        generator.appliesPreferredTrackTransform = YES;
        //设置最大尺寸
        generator.maximumSize = track.naturalSize;
        CMTime actualTime;
        NSError *error = nil;
        CGImageRef imageRef = [generator copyCGImageAtTime:CMTimeMakeWithSeconds(seconds, asset.duration.timescale) actualTime:&actualTime error:&error];
        dispatch_async(dispatch_get_main_queue(), ^{
            if (imageRef) {
                UIImage *thumbImage = [[UIImage alloc]initWithCGImage:imageRef];
                handle(thumbImage,error);
            } else {
                NSLog(@"截图失败==%@",error.domain.description);
                handle(nil,error);
            }
        });
    });
}