我正在尝试将一个UIImage
保存为NSData
,然后在Swift中读取NSData
以获取新的UIImage
。为了将UIImage
转换为NSData
,我正在使用以下代码:
let imageData: NSData = UIImagePNGRepresentation(myImage)
我如何将imageData
(即NSData
) 转换回一个新的 UIImage
?
UIImage(data:imageData,scale:1.0)
假设图像的比例为1。
在Swift 4.2中,使用以下代码获取Data()。
image.pngData()
谢谢,这对我很有帮助。已转换为Swift 3并且能正常工作。
保存图片:
let data = UIImagePNGRepresentation(image)
加载图片:
let image = UIImage(data: data)
let imagePt = UIImage(data: caminhodaImagem)
这不够吗? - superarts.org使用imageWithData:
方法,它在Swift中被翻译为UIImage(data:)
。
let image : UIImage = UIImage(data: imageData)
现在在 Swift 4.2 中,你可以使用UIImage
的新实例方法pngData()
来获取图像数据
let profileImage = UIImage(named:"profile")!
let imageData = profileImage.pngData()
guard let image = UIImage(named: "img") else { return }
let jpegData = image.jpegData(compressionQuality: 1.0)
let pngData = image.pngData()
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
}
}
}
// 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")
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
}
}
}
}
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)
问题
在处理图像时需要耗费大量的CPU和内存资源。因此,在这种情况下,最好遵循以下几条规则:
- 不要在主队列上运行jpegData(compressionQuality:)
- 同时只运行一个jpegData(compressionQuality:)
错误的示例:
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")
}
}
正确:
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")
}
}
图片转数据:-
if let img = UIImage(named: "xxx.png") {
let pngdata = img.pngData()
}
if let img = UIImage(named: "xxx.jpeg") {
let jpegdata = img.jpegData(compressionQuality: 1)
}
数据到图片:
guard let image = UIImage(data: pngData) else { return }
保存数据:
如果您想在MainStoryBoard的imageView上保存“image”数据,可以在StoryBoard中使用以下代码来实现。
let image = UIImagePNGRepresentation(imageView.image!) as NSData?
将“图像”加载到imageView中: 仔细看感叹号“!”和问号“?”是否与这个非常相似。
imageView.image = UIImage(data: image as! Data)
为了安全地执行代码,请使用带有 Data
的 if-let
块来防止应用程序崩溃,因为函数 UIImagePNGRepresentation
返回一个可选值。
if let img = UIImage(named: "TestImage.png") {
if let data:Data = UIImagePNGRepresentation(img) {
// Handle operations with data here...
}
}
注意: Data 是Swift 3+的类。在Swift 3+中请使用Data代替NSData。
通用图像操作(例如png和jpg):
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...
}
}
通过使用扩展功能:
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...
}
}
Swift 5
让您创建的图像作为UIImage成为图像
image.pngData() as NSData?
使用此方法可获得简单的解决方案
static var UserProfilePhoto = UIImage()
guard let image = UIImage(named: "Photo") else { return }
guard let pngdata = image.pngData() else { return }
UserProfilePhoto = UIImage(data: pngdata)!