在不使用MPMoviePlayer的情况下在iPhone上制作动画图像(如电影)的方法

import AVFoundation

let fileManager = FileManager.default
let urls = fileManager.urls(for: .documentDirectory, in: .userDomainMask)
let fileUrl = urls[0].appendingPathComponent("output.mp4")

do {
    try FileManager.default.removeItem(at: fileUrl)
} catch {
    print("Error removing file")
}

guard let assetWriter = try? AVAssetWriter(outputURL: fileUrl, fileType: .mp4) else {
    print("Error creating AVAssetWriter")
    return
}

let videoOutputSettings: [String: Any] = [
    AVVideoCodecKey: AVVideoCodecType.h264,
    AVVideoWidthKey: 360,
    AVVideoHeightKey: 480,
    AVVideoCompressionPropertiesKey: [
        AVVideoAverageBitRateKey: 2000000,
        AVVideoProfileLevelKey: AVVideoProfileLevelH264High40
    ]
]

let videoWriterInput = AVAssetWriterInput(mediaType: .video, outputSettings: videoOutputSettings)
videoWriterInput.expectsMediaDataInRealTime = true

if assetWriter.canAdd(videoWriterInput) {
    assetWriter.add(videoWriterInput)
} else {
    print("Couldn't add video input to asset writer")
    return
}

let eaglContext = EAGLContext(api: .openGLES2)
let ciContext = CIContext(eaglContext: eaglContext!)

let displayLink = CADisplayLink(target: self, selector: #selector(renderLoop))
displayLink.preferredFramesPerSecond = 30
displayLink.add(to: .current, forMode: .common)

@objc func renderLoop() {
    // Create CIImage
    let ciImage = CIImage(image: UIImage(named: "example.jpg")!)

    // Render CIImage to CVPixelBufferRef
    let pixelBuffer: CVPixelBuffer? = ciContext.newPixelBuffer(from: ciImage)

    if let pixelBuffer = pixelBuffer {
        let presentationTime = CMTimeMake(value: Int64(frameCount), timescale: 30)
        videoWriterInput.append(pixelBuffer, withPresentationTime: presentationTime)
        frameCount += 1
    }
}

assetWriter.finishWriting {
    print("Finished writing video")
}