iOS 仿抖音图片转视频效果

本图片转视频加入了图片缩放和转场效果，通过向一个本地的黑色背景视频black.mp4加入图片的缩放和转场动画来实现

- (void)videoAnimation:(NSArray *)imgArr (void(^)(NSURL*))success{

//每张图片显示的时间

NSInteger picTime = 3;

//获取背景视频地址

    NSString *videoPath = [[NSBundle mainBundle] pathForResource:@"black" ofType:@"mp4"];

    NSString *cachePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"imagesComposition.mp4"];

    if ([[NSFileManager defaultManager] fileExistsAtPath:cachePath])

        {

            [[NSFileManager defaultManager] removeItemAtPath:cachePath error:nil];

        }

    NSURL    *exportUrl = [NSURLfileURLWithPath:cachePath];

//视频时长

    NSInteger tempDuration =self.imgArr.count*picTime+0.1*self.imgArr.count;

    NSInteger duration = tempDuration >180.0?180.0:tempDuration;

//通过本地视频地址创建视频源

    AVURLAsset*videoAsset = [AVURLAsset assetWithURL:[NSURL fileURLWithPath:videoPath]];

    AVMutableComposition *mutableComposition = [AVMutableComposition composition];

//获取视频轨道

    AVMutableCompositionTrack *videoCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];

    AVAssetTrack *videoAssetTrack = [videoAsset tracksWithMediaType:AVMediaTypeVideo].firstObject;

    CMTimeValue value = videoAsset.duration.timescale* duration;

    CMTime endTime =CMTimeMake(value, videoAsset.duration.timescale);

    CMTimeRange timeR = CMTimeRangeMake(kCMTimeZero, endTime);

    [videoCompositionTrack insertTimeRange:timeR ofTrack:videoAssetTrack atTime:kCMTimeZero error:nil];

//获取视频轨道上的素材添加到最终合成的视频轨道中

    AVMutableVideoCompositionInstruction *videoCompostionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];

    videoCompostionInstruction.timeRange= timeR;

    AVMutableVideoCompositionLayerInstruction *videoLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoCompositionTrack];

    [videoLayerInstruction setTransform:videoAssetTrack.preferredTransform atTime:kCMTimeZero];

    [videoLayerInstruction setOpacity:0 atTime:endTime];

    videoCompostionInstruction.layerInstructions=@[videoLayerInstruction];

    AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition];

    mutableVideoComposition.renderSize=CGSizeMake(720,1280);

    mutableVideoComposition.frameDuration=CMTimeMake(1,25);

    mutableVideoComposition.instructions=@[videoCompostionInstruction];

//创建一个存放图片图层的数组

    CALayer*bgLayer = [[CALayer alloc]init];

    bgLayer.frame=CGRectMake(0,0,720,1280);

    bgLayer.position=CGPointMake(360,640);

    NSMutableArray *imageLayers = [NSMutableArray array];

    for(UIImage*img in self.imgArr) {

        CALayer*imageL = [[CALayer alloc]init];

        imageL.contents= (__bridgeid)img.CGImage;

        imageL.bounds=CGRectMake(0,0,720,1280);

        imageL.contentsGravity = kCAGravityResizeAspect;

        imageL.backgroundColor = [UIColor blackColor].CGColor;

        imageL.anchorPoint=CGPointMake(0,0);

        [bgLayer addSublayer:imageL];

        [imageLayers addObject:imageL];

    }

//图片图层添加动画效果

        [imageLayers enumerateObjectsUsingBlock:^(id  _Nonnullobj,NSUIntegeridx,BOOL*_Nonnullstop) {

            CABasicAnimation*animation1 = [CABasicAnimation animationWithKeyPath:@"transform.scale"];

            animation1.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

            animation1.removedOnCompletion=false;

            animation1.beginTime=1.1+picTime* idx;

            animation1.fromValue= [NSNumber numberWithFloat:1.0];

            animation1.toValue= [NSNumber numberWithFloat:1.1];

            animation1.duration=2;

            animation1.fillMode=kCAFillModeBoth;

            [(CALayer*)obj addAnimation:animation1 forKey:@"transform.scale"];

            CABasicAnimation*animation2 = [CABasicAnimation animationWithKeyPath:@"position"];

            animation2.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

            animation2.removedOnCompletion=false;

            animation2.beginTime=0.1+picTime* idx;

            animation2.fromValue= [NSValue valueWithCGPoint:CGPointMake(720* idx,0)];

            animation2.toValue= [NSValue valueWithCGPoint:CGPointMake(0,0)];

            animation2.duration=1;

            animation2.fillMode=kCAFillModeBoth;

            [(CALayer*)obj addAnimation:animation2forKey:@"position"];

        }];

//创建视频图层并添加生成的图片动画

        CALayer*parentLayer = [[CALayer alloc]init];

        CALayer*videoLayer = [[CALayer alloc]init];

        parentLayer.frame=CGRectMake(0,0,720,1280);

        videoLayer.frame=CGRectMake(0,0,720,1280);

        [parentLayer addSublayer:videoLayer];

        [parentLayer addSublayer:bgLayer];

        parentLayer.geometryFlipped=YES;

//视频图层加入最终合成的视频轨道中

    mutableVideoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

//导出视频

    AVAssetExportSession *assetExport = [AVAssetExportSession exportSessionWithAsset:mutableComposition presetName:AVAssetExportPresetHighestQuality];

    assetExport.outputFileType = AVFileTypeMPEG4;

    assetExport.outputURL= exportUrl;

    assetExport.shouldOptimizeForNetworkUse = YES;

    assetExport.videoComposition= mutableVideoComposition;

    [assetExport exportAsynchronouslyWithCompletionHandler:^{

        if (assetExport.status == AVAssetExportSessionStatusCompleted) {

            if(success) {

                success(exportUrl);

            }

        }

    }];

}