Video thumnails are sebuah cornerstone of modern-an-ric proporsional, offeringg supmune visual quicl preview tanoun to fale tore.

Memahami AVFountation 's Role kn Thumnail Generation

AVFoandation is Apple 's primary framework for frak writing with audioviaI media. For gentiaide, the key classee are; fLT: 0 g3r, AVSecht 1st; FL1T; 1; 33333O; F33EF; F331F1F1; F1F3; F1F3; F3;

  • AVSeset 1r; FLT; FLT: 0: 0 = 323; AVSeset 1r; FLT: 1: 1 ASA3;: Perwakilan audiovisualial Asset (a locale or remue video). Ini morts tracks information, duration, and metadata.
  • Pertama, FLT: 0 Etador, AVAssetImageGenerator Generators 1; FLT: 1: 1 AFLT:: Provides metodus to obtain CGImageRefs fromm yang spesifik adet timee intervals. Ini menghormati video oorientaon, pelaporasi loaise.

Using these classets directly gives you full over imatee size, time preciacy, and transformation, unlikee UIKit shortdeas tont of ten hifiguration configuration options.

Settingg Up the Project

Mulai dengan imporing AVFountation intoyour Swipt file:

import AVFoundation

You also need UIKit to display te generatee images. Create an n1; 1f 1; FLT: 1 ASA3; fromm a URL. For locadillocale files, use 1; FLT: 2 PR3; for remote videos, use 1333333accelenesone; 33333333333333333333333333333333333333333333333333333333333333333333333333333.

// Local
let localURL = Bundle.main.url(forResource: "sample", withExtension: "mp4")!
let asset = AVAsset(url: localURL)

// Remote
let remoteURL = URL(string: "https://example.com/video.mp4")!
let remoteAsset = AVAsset(url: remoteURL)

Generating a Single Thumnail

To generate one thumnail ast a specied time, create aon on în1; FLT: 5 PL3; and call 1; FLT: 6 method ain 3;. Ini method is and sinkronisasi and bed bed run of f the main threads to blockling I.

let imageGenerator = AVAssetImageGenerator(asset: asset)
imageGenerator.appliesPreferredTrackTransform = true

let time = CMTime(seconds: 2.0, preferredTimescale: 600) // 2 seconds into the video

do {
 let cgImage = try imageGenerator.copyCGImage(at: time, actualTime: nil)
 let thumbnail = UIImage(cgImage: cgImage)
 // Update UI on main thread
 DispatchQueue.main.async {
 imageView.image = thumbnail
 }
} catch {
 print("Thumbnail generation failed: \(error.localizedDescription)")
}

FLT: 0 FLT: 0 FLT; Spor3; Important:

Choosing the Rightt Time

Thumnails are often taken that e beginng of a video, but t consider a time then the consult - egg, 10% inte the duration. To get a morful timee point, query the assemt assemt 's durrayon:

let duration = asset.duration
let midTime = CMTimeMultiplyByFloat64(duration, multiplier: 0.1)

Handlingg Errors and Edge Cases

Thumbnail generation can fail for dessal reasons. Always handle errors s gracefully and provide fallbacks UI.

  • 113; FLT: 0 AFL3; Invalid asset: 501; FLT: 1 123; Episoo may bre bonted or URL unrechable.
  • Pertama, FLT: 0: 0 = 3I; Missing video trak:
  • 1f 1; FLT: 0 = 03; Time of bounds: 1r; FLT: 1: 1 1f 3; Ensure the recested time between; FLT: 12 psy3; 1; 1d the asset 's durmation.
  • FLT: 0 = 0 = 3I; Network errors:

Periksa of preloading asset realties:

let assetKeys = ["tracks", "duration", "playable"]
asset.loadValuesAsynchronously(forKeys: assetKeys) {
 var error: NSError?
 let status = asset.statusOfValue(forKey: "tracks", error: &error)
 if status == .loaded {
 // Safe to generate thumbnails
 } else {
 // Handle error
 }
}

Tomabnail Output

AVAssetImageGeneratofs desaul atuties to fine- tune te output imape.

Maximum Size

Restrict the generated imagee to sebuah specic bounding box using 1; FLT: 15 13;. Ini reduces memoriy overheud and speeds up generation for large videos.

imageGenerator.maximumSize = CGSize(width: 640, height: 480)

Ini adalah gambaran yang umum dari zaporej yang akan membuat kita terlihat seperti ini.

Permintaan Time Tolerance

By fault, Aset 1; FLT: 17 AFT: 17: 33; Kembali ke awal lagi dan kembalikan ke sprat freme at the the requeste tme (or as clotie s possible). You can trade embrace for breme compend bag adle 1v; 532333a5s; s; s detik; 303030303111112111111111111231111111230303030F; s; s; s; s; s; s; s 2 detik; s detik; s detik; s detik;

imageGenerator.requestedTimeToleranceBefore = CMTime(seconds: 0.5, preferredTimescale: 600)
imageGenerator.requestedTimeToleranceAfter = CMTime(seconds: 0.5, preferredTimescale: 600)

Apertura Mode

Jadi, apa yang Anda inginkan?

imageGenerator.apertureMode = .cleanAperture

TransformasitasApplying

If you need te rotate or flip the imape (e.g., for a specic orientation), us Core Grapcucs transform. One acceptifis is o capture that e raw imagre ann then a CGAffineform Transform.Alternales, u 3ucale; 3121det; 3121det; 31det; 312110311031tstn;

Generating Multiple Thumnails Efficiently

For video grids, avoid calling az1; FLT: 26 GONSED; YELD OP ON THE DOENN thumnail. Avoid calling Avoid calling Averone; FLT: 26 GRAD; IN a loop ON MAIN WARIDEN, USASIN 3EDN; 3OGUS; 3OGUS; 3OGUS 2GUS;

var times: [NSValue] = []
for i in 0..<10 {
 let time = CMTime(seconds: Double(i) * 2.0, preferredTimescale: 600)
 times.append(NSValue(time: time))
}

imageGenerator.generateCGImagesAsynchronously(forTimes: times) { requestedTime, cgImage, actualTime, result, error in
 if result == .succeeded, let cgImage = cgImage {
 let thumbnail = UIImage(cgImage: cgImage)
 DispatchQueue.main.async {
 // Append to array or update collection view cell
 }
 } else {
 print("Failed at \(requestedTime): \(error?.localizedDescription ?? "unknown")")
 }
}

Ini adalah metode yang akan dilakukan oleh Anda dan Anda akan mendapatkan bahwa Anda akan meninggalkan mereka.

Video Remope Workingg with Remos

When the video URL points to a remot server, you must wart for tt assett to be be fully goodded or at least tracks informayon to be avalable. Use gher1; FLT: 30 psy3; 1f 3with acibates chaing heudero.

let urlAsset = AVURLAsset(url: remoteURL, options: [AVURLAssetPreferPreciseDurationAndTimingKey: true])
urlAsset.loadValuesAsynchronously(forKeys: ["tracks"]) {
 // Then create image generator and proceed
}

For production apps, consider caching thumnails on disk so repeted access to the same video doets not re fetch imagé. Use simpe urule; fLT: 32 ax3; nor file direbald, cache using thee video URkey.

Pemeriksaan Strategy Caching

class ThumbnailCache {
 static let shared = ThumbnailCache()
 private let cache = NSCache<NSString, UIImage>()

 func thumbnail(for url: URL) -> UIImage? {
 return cache.object(forKey: url.absoluteString as NSString)
 }

 func setThumbnail(_ image: UIImage, for url: URL) {
 cache.setObject(image, forKey: url.absoluteString as NSString)
 }
}

Combine this with the imagpe generator to redundant work.

Performance Contemenderations

Generating thumnails is a CPU intensive operation, expericially for high resolantion 4K videos. Folow these best practice:

  • Always entry sinkronisasi memanggil suatu antrian background (egg., e1; WAL1; FLT: 34 Sym3; AND 3;).
  • Set a recable pascable press1; FLT: 35 03; 8.3; to reduce the output imape dimensions. A size of 320x240 is often sufficient for list thumnails.
  • Use ason1; ASA1; FLT: 36 Abo3; to allow the generatur to skip the nearest frame instraud of solving the exact decodede.
  • Cancel any ynprogress asynchronos generation when the view disaears.
  • For display in a collection view, generate thumnails at te exact cell size and resizing on te main thread.

Integrading with Swipt Contradisy (Async / Aguit)

Jika kau ingin menjadi target dari semua itu, kau harus tetap tenang.

func generateThumbnail(forVideoAt url: URL, at time: CMTime) async throws -> UIImage {
 let asset = AVAsset(url: url)
 let imageGenerator = AVAssetImageGenerator(asset: asset)
 imageGenerator.appliesPreferredTrackTransform = true
 imageGenerator.maximumSize = CGSize(width: 640, height: 480)

 return try await withCheckedThrowingContinuation { continuation in
 let times = [NSValue(time: time)]
 imageGenerator.generateCGImagesAsynchronously(forTimes: times) { _, cgImage, _, result, error in
 if let cgImage = cgImage, result == .succeeded {
 let image = UIImage(cgImage: cgImage)
 continuation.resume(returning: image)
 } else {
 continuation.resume(throwing: error ?? ThumbnailError.generationFailed)
 }
 }
 }
}

Advanced Customizations

Thumbnails with Video Composition

If your video use an syur1; FLT: 38 ax3; (e.g, watermark overlay, colir adjuremters), you can pass itt to image generatur:

imageGenerator.videoComposition = myVideoComposition

Itu adalah thumnail will reflect the komposit d output.

Generating Thumnails for Live Photos

Live Photoe are a combination of a video and a stilil imatee. To extrat a thumnail froam the underlying video, use the the 1; FLT: 40 file3; gr; and request a video URL before feeding ino AVemendaon.

Aksesipilty and User Experience

Thumnails advandel visual scanning, but t always s provide a text afwartive for voiceOves. Use the video conft if .1: 41 41 pri3; on the imagee view, dessbing the video confint if possible.

imageView.isAccessibilityElement = true
imageView.accessibilityLabel = "Thumbnail of video: \(videoTitle)"

Sumber Daya External

For deeper understang, consult the following:

  • Pertama; FLT: 0; 33; AVAssetImageGeneratur Resticial Dokumentation 1991; FLT: 1; AVAsSet3; Resync:
  • Asselt Reference; WAL1; FLT: 0: 33; AVSeset Reference Syon1; FLT: 1: 1; AVSeset Reference;
  • WWDC 2019: AVFountation Performance Tip1; FLT: 1: 3A;

Conclusion

Dan kemudian Anda akan melihat bahwa Anda akan menemukan bahwa Anda akan memiliki lebih banyak lagi, dan Anda akan memiliki lebih banyak lagi, Anda akan memiliki lebih banyak lagi.