iOS -应用CIFilter合并多个视频

import AVFoundation
import CoreImage

let composition = AVMutableComposition()

let asset1 = AVURLAsset(url: videoURL1)
let asset2 = AVURLAsset(url: videoURL2)

let track1 = composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
let track2 = composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)

try track1?.insertTimeRange(CMTimeRange(start: .zero, duration: asset1.duration), of: asset1.tracks(withMediaType: .video)[0], at: .zero)
try track2?.insertTimeRange(CMTimeRange(start: .zero, duration: asset2.duration), of: asset2.tracks(withMediaType: .video)[0], at: asset1.duration)

let videoComposition = AVMutableVideoComposition()
videoComposition.renderSize = CGSize(width: videoWidth, height: videoHeight)
videoComposition.frameDuration = CMTime(value: 1, timescale: 30)

let filter = CIFilter(name: "CISourceOverCompositing")
let compositionFilter = CIFilterVideoCompositionProvider(filter: filter, source: composition, trackID: trackID)
videoComposition.customVideoCompositorClass = compositionFilter

let exportSession = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetHighestQuality)
exportSession?.outputURL = outputURL
exportSession?.outputFileType = .mp4

exportSession?.exportAsynchronously(completionHandler: {
    // 合并视频导出完成后的处理
})