问题
I’d like to create an animated GIF in SwiftUI.
I tried:
- Adding a GIF to my assets and loading that through
Image(“myGif”) - Creating a UIImage through downloading a GIF image, and passing that to
Image - Using this script to create a UIImage and then repeating #2.
None of the above worked, has anyone figured this out?
回答1:
You can do it by creating UIViewRepresentable from UIView.
UIViewRepresentable create View for you, which you can use it in SwiftUI class.
Step1: Create UIView class for Gifview
class GIFPlayerView: UIView {
private let imageView = UIImageView()
convenience init(gifName: String) {
self.init()
let gif = UIImage.gif(asset: gifName)
imageView.image = gif
imageView.contentMode = .scaleAspectFit
self.addSubview(imageView)
}
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func layoutSubviews() {
super.layoutSubviews()
imageView.frame = bounds
}
}
Step2: Create UIViewRepresentable class for GifView
struct GIFView: UIViewRepresentable {
var gifName: String
func updateUIView(_ uiView: UIView, context: UIViewRepresentableContext<GIFView>) {
}
func makeUIView(context: Context) -> UIView {
return GIFPlayerView(gifName: gifName)
}
}
Step3: Use that UIViewRepresentable view.
var body: some View {
VStack {
GIFView(gifName: "your gif name")
}
}
Note: Extension for Gif to Image. Refer: https://stackoverflow.com/a/45554784
extension UIImageView {
public func loadGif(name: String) {
DispatchQueue.global().async {
let image = UIImage.gif(name: name)
DispatchQueue.main.async {
self.image = image
}
}
}
@available(iOS 9.0, *)
public func loadGif(asset: String) {
DispatchQueue.global().async {
let image = UIImage.gif(asset: asset)
DispatchQueue.main.async {
self.image = image
}
}
}
}
extension UIImage {
public class func gif(data: Data) -> UIImage? {
// Create source from data
guard let source = CGImageSourceCreateWithData(data as CFData, nil) else {
print("SwiftGif: Source for the image does not exist")
return nil
}
return UIImage.animatedImageWithSource(source)
}
public class func gif(url: String) -> UIImage? {
// Validate URL
guard let bundleURL = URL(string: url) else {
print("SwiftGif: This image named \"\(url)\" does not exist")
return nil
}
// Validate data
guard let imageData = try? Data(contentsOf: bundleURL) else {
print("SwiftGif: Cannot turn image named \"\(url)\" into NSData")
return nil
}
return gif(data: imageData)
}
public class func gif(name: String) -> UIImage? {
// Check for existance of gif
guard let bundleURL = Bundle.main
.url(forResource: name, withExtension: "gif") else {
print("SwiftGif: This image named \"\(name)\" does not exist")
return nil
}
// Validate data
guard let imageData = try? Data(contentsOf: bundleURL) else {
print("SwiftGif: Cannot turn image named \"\(name)\" into NSData")
return nil
}
return gif(data: imageData)
}
@available(iOS 9.0, *)
public class func gif(asset: String) -> UIImage? {
// Create source from assets catalog
guard let dataAsset = NSDataAsset(name: asset) else {
print("SwiftGif: Cannot turn image named \"\(asset)\" into NSDataAsset")
return nil
}
return gif(data: dataAsset.data)
}
internal class func delayForImageAtIndex(_ index: Int, source: CGImageSource!) -> Double {
var delay = 0.1
// Get dictionaries
let cfProperties = CGImageSourceCopyPropertiesAtIndex(source, index, nil)
let gifPropertiesPointer = UnsafeMutablePointer<UnsafeRawPointer?>.allocate(capacity: 0)
defer {
gifPropertiesPointer.deallocate()
}
let unsafePointer = Unmanaged.passUnretained(kCGImagePropertyGIFDictionary).toOpaque()
if CFDictionaryGetValueIfPresent(cfProperties, unsafePointer, gifPropertiesPointer) == false {
return delay
}
let gifProperties: CFDictionary = unsafeBitCast(gifPropertiesPointer.pointee, to: CFDictionary.self)
// Get delay time
var delayObject: AnyObject = unsafeBitCast(
CFDictionaryGetValue(gifProperties,
Unmanaged.passUnretained(kCGImagePropertyGIFUnclampedDelayTime).toOpaque()),
to: AnyObject.self)
if delayObject.doubleValue == 0 {
delayObject = unsafeBitCast(CFDictionaryGetValue(gifProperties,
Unmanaged.passUnretained(kCGImagePropertyGIFDelayTime).toOpaque()), to: AnyObject.self)
}
if let delayObject = delayObject as? Double, delayObject > 0 {
delay = delayObject
} else {
delay = 0.1 // Make sure they're not too fast
}
return delay
}
internal class func gcdForPair(_ lhs: Int?, _ rhs: Int?) -> Int {
var lhs = lhs
var rhs = rhs
// Check if one of them is nil
if rhs == nil || lhs == nil {
if rhs != nil {
return rhs!
} else if lhs != nil {
return lhs!
} else {
return 0
}
}
// Swap for modulo
if lhs! < rhs! {
let ctp = lhs
lhs = rhs
rhs = ctp
}
// Get greatest common divisor
var rest: Int
while true {
rest = lhs! % rhs!
if rest == 0 {
return rhs! // Found it
} else {
lhs = rhs
rhs = rest
}
}
}
internal class func gcdForArray(_ array: [Int]) -> Int {
if array.isEmpty {
return 1
}
var gcd = array[0]
for val in array {
gcd = UIImage.gcdForPair(val, gcd)
}
return gcd
}
internal class func animatedImageWithSource(_ source: CGImageSource) -> UIImage? {
let count = CGImageSourceGetCount(source)
var images = [CGImage]()
var delays = [Int]()
// Fill arrays
for index in 0..<count {
// Add image
if let image = CGImageSourceCreateImageAtIndex(source, index, nil) {
images.append(image)
}
// At it's delay in cs
let delaySeconds = UIImage.delayForImageAtIndex(Int(index),
source: source)
delays.append(Int(delaySeconds * 1000.0)) // Seconds to ms
}
// Calculate full duration
let duration: Int = {
var sum = 0
for val: Int in delays {
sum += val
}
return sum
}()
// Get frames
let gcd = gcdForArray(delays)
var frames = [UIImage]()
var frame: UIImage
var frameCount: Int
for index in 0..<count {
frame = UIImage(cgImage: images[Int(index)])
frameCount = Int(delays[Int(index)] / gcd)
for _ in 0..<frameCount {
frames.append(frame)
}
}
// Heyhey
let animation = UIImage.animatedImage(with: frames,
duration: Double(duration) / 1000.0)
return animation
}
}
来源：https://stackoverflow.com/questions/57024662/how-to-create-an-animated-gif