將 UIImage 轉換為 NSData 並在 Swift 中轉換回 UIImage？

Question

我正在嘗試將UIImage保存到NSData ，然后在 Swift 中將NSData讀回新的UIImage 。 要將UIImage轉換為NSData我使用以下代碼：

let imageData: NSData = UIImagePNGRepresentation(myImage)

如何將imageData （即NSData ）轉換回新的UIImage ？

Answer 1

UIImage(data:imageData,scale:1.0)假設圖像的比例為 1。

在 swift 4.2 中，使用下面的代碼獲取數據（）。

image.pngData()

Answer 2

謝謝。 幫了我很多。 轉換為 Swift 3 並開始工作

保存： let data = UIImagePNGRepresentation(image)

加載： let image = UIImage(data: data)

Answer 3

使用imageWithData:方法，該方法被轉換為 Swift 為UIImage(data:)

let image : UIImage = UIImage(data: imageData)

Answer 4

現在雨燕4.2，你可以使用pngData()的新實例方法UIImage從圖像獲取數據

let profileImage = UIImage(named:"profile")!
let imageData = profileImage.pngData()

Answer 5

細節

• Xcode 10.2.1 (10E1001)，Swift 5

解決方案1

guard let image = UIImage(named: "img") else { return }
let jpegData = image.jpegData(compressionQuality: 1.0)
let pngData = image.pngData()

---

解決方案 2.1

extension UIImage {
    func toData (options: NSDictionary, type: CFString) -> Data? {
        guard let cgImage = cgImage else { return nil }
        return autoreleasepool { () -> Data? in
            let data = NSMutableData()
            guard let imageDestination = CGImageDestinationCreateWithData(data as CFMutableData, type, 1, nil) else { return nil }
            CGImageDestinationAddImage(imageDestination, cgImage, options)
            CGImageDestinationFinalize(imageDestination)
            return data as Data
        }
    }
}

解決方案2.1的使用

// about properties: https://developer.apple.com/documentation/imageio/1464962-cgimagedestinationaddimage
let options: NSDictionary =     [
    kCGImagePropertyOrientation: 6,
    kCGImagePropertyHasAlpha: true,
    kCGImageDestinationLossyCompressionQuality: 0.5
]

// https://developer.apple.com/documentation/mobilecoreservices/uttype/uti_image_content_types
guard let data = image.toData(options: options, type: kUTTypeJPEG) else { return }
let size = CGFloat(data.count)/1000.0/1024.0
print("\(size) mb")

---

解決方案 2.2

extension UIImage {

    func toJpegData (compressionQuality: CGFloat, hasAlpha: Bool = true, orientation: Int = 6) -> Data? {
        guard cgImage != nil else { return nil }
        let options: NSDictionary =     [
                                            kCGImagePropertyOrientation: orientation,
                                            kCGImagePropertyHasAlpha: hasAlpha,
                                            kCGImageDestinationLossyCompressionQuality: compressionQuality
                                        ]
        return toData(options: options, type: .jpeg)
    }

    func toData (options: NSDictionary, type: ImageType) -> Data? {
        guard cgImage != nil else { return nil }
        return toData(options: options, type: type.value)
    }
    // about properties: https://developer.apple.com/documentation/imageio/1464962-cgimagedestinationaddimage
    func toData (options: NSDictionary, type: CFString) -> Data? {
        guard let cgImage = cgImage else { return nil }
        return autoreleasepool { () -> Data? in
            let data = NSMutableData()
            guard let imageDestination = CGImageDestinationCreateWithData(data as CFMutableData, type, 1, nil) else { return nil }
            CGImageDestinationAddImage(imageDestination, cgImage, options)
            CGImageDestinationFinalize(imageDestination)
            return data as Data
        }
    }

    // https://developer.apple.com/documentation/mobilecoreservices/uttype/uti_image_content_types
    enum ImageType {
        case image // abstract image data
        case jpeg                       // JPEG image
        case jpeg2000                   // JPEG-2000 image
        case tiff                       // TIFF image
        case pict                       // Quickdraw PICT format
        case gif                        // GIF image
        case png                        // PNG image
        case quickTimeImage             // QuickTime image format (OSType 'qtif')
        case appleICNS                  // Apple icon data
        case bmp                        // Windows bitmap
        case ico                        // Windows icon data
        case rawImage                   // base type for raw image data (.raw)
        case scalableVectorGraphics     // SVG image
        case livePhoto                  // Live Photo

        var value: CFString {
            switch self {
            case .image: return kUTTypeImage
            case .jpeg: return kUTTypeJPEG
            case .jpeg2000: return kUTTypeJPEG2000
            case .tiff: return kUTTypeTIFF
            case .pict: return kUTTypePICT
            case .gif: return kUTTypeGIF
            case .png: return kUTTypePNG
            case .quickTimeImage: return kUTTypeQuickTimeImage
            case .appleICNS: return kUTTypeAppleICNS
            case .bmp: return kUTTypeBMP
            case .ico: return kUTTypeICO
            case .rawImage: return kUTTypeRawImage
            case .scalableVectorGraphics: return kUTTypeScalableVectorGraphics
            case .livePhoto: return kUTTypeLivePhoto
            }
        }
    }
}

解決方案2.2的使用

let compressionQuality: CGFloat = 0.4
guard let data = image.toJpegData(compressionQuality: compressionQuality) else { return }
printSize(of: data)

let options: NSDictionary =     [
                                    kCGImagePropertyHasAlpha: true,
                                    kCGImageDestinationLossyCompressionQuality: compressionQuality
                                ]
guard let data2 = image.toData(options: options, type: .png) else { return }
printSize(of: data2)

---

問題

圖像表示會占用大量的 CPU 和內存資源。 因此，在這種情況下，最好遵循以下幾條規則：

- 不要在主隊列上運行 jpegData(compressionQuality:)

- 同時只運行一個 jpegData(compressionQuality:)

錯誤的：

for i in 0...50 {
    DispatchQueue.global(qos: .utility).async {
        let quality = 0.02 * CGFloat(i)
        //let data = image.toJpegData(compressionQuality: quality)
        let data = image.jpegData(compressionQuality: quality)
        let size = CGFloat(data!.count)/1000.0/1024.0
        print("\(i), quality: \(quality), \(size.rounded()) mb")
    }
}

對：

let serialQueue = DispatchQueue(label: "queue", qos: .utility, attributes: [], autoreleaseFrequency: .workItem, target: nil)

for i in 0...50 {
    serialQueue.async {
        let quality = 0.02 * CGFloat(i)
        //let data = image.toJpegData(compressionQuality: quality)
        let data = image.jpegData(compressionQuality: quality)
        let size = CGFloat(data!.count)/1000.0/1024.0
        print("\(i), quality: \(quality), \(size.rounded()) mb")
    }
}

鏈接

• UTI 圖像內容類型
• CGImageDestinationAddImage( : :_ :)
• 關於內存的思考：在 Swift 中將 UIImage 轉換為數據
• 不同的調整大小技術

Answer 6

保存為數據：

從 StoryBoard 中，如果您想在 MainStoryBoard 的 imageView 上保存“圖像”數據，以下代碼將起作用。

let image = UIImagePNGRepresentation(imageView.image!) as NSData?

將“圖像”加載到 imageView：查看感嘆號“！”、“？” 是否與此完全相同。

imageView.image = UIImage(data: image as! Data)

在此過程中，“NSData”類型會自動轉換為“Data”類型。

Answer 7

為了代碼的安全執行，使用帶有Data if-let塊來防止應用程序崩潰 & ，因為函數UIImagePNGRepresentation返回一個可選值。

if let img = UIImage(named: "TestImage.png") {
    if let data:Data = UIImagePNGRepresentation(img) {
       // Handle operations with data here...         
    }
}

注意：數據是 Swift 3+ 類。 在 Swift 3+ 中使用 Data 而不是 NSData

通用圖像操作（如 png 和 jpg 兩者）：

if let img = UIImage(named: "TestImage.png") {  //UIImage(named: "TestImage.jpg")
        if let data:Data = UIImagePNGRepresentation(img) {
               handleOperationWithData(data: data)     
        } else if let data:Data = UIImageJPEGRepresentation(img, 1.0) {
               handleOperationWithData(data: data)     
        }
}

*******
func handleOperationWithData(data: Data) {
     // Handle operations with data here...
     if let image = UIImage(data: data) {
        // Use image...
     }
}

通過使用擴展：

extension UIImage {

    var pngRepresentationData: Data? {
        return UIImagePNGRepresentation(self)
    }

    var jpegRepresentationData: Data? {
        return UIImageJPEGRepresentation(self, 1.0)
    }
}

*******
if let img = UIImage(named: "TestImage.png") {  //UIImage(named: "TestImage.jpg")
      if let data = img.pngRepresentationData {
              handleOperationWithData(data: data)     
      } else if let data = img.jpegRepresentationData {
              handleOperationWithData(data: data)     
     }
}

*******
func handleOperationWithData(data: Data) {
     // Handle operations with data here...
     if let image = UIImage(data: data) {
        // Use image...
     }
}

Answer 8

圖像到數據：-

    if let img = UIImage(named: "xxx.png") {
        let pngdata = img.pngData()
    }

   if let img = UIImage(named: "xxx.jpeg") {
        let jpegdata = img.jpegData(compressionQuality: 1)
    }

數據到圖像：-

 let image = UIImage(data: pngData)

Answer 9

斯威夫特 5

讓您創建為 UIImage 的圖像成為圖像

image.pngData() as NSData? 

Answer 10

 imag.jpegData(compressionQuality: 0.2)

Answer 11

將此用於簡單的解決方案

static var UserProfilePhoto = UIImage()
guard let image = UIImage(named: "Photo") else { return }
guard let pngdata = image.pngData() else { return }
UserProfilePhoto = UIImage(data: pngdata)!