Convert UIImage to NSData and convert back to UIIm

问题:

I'm trying to save a UIImage to NSData and then read the NSData back to a new UIImage in Swift. To convert the UIImage to NSData I'm using the following code:

let imageData: NSData = UIImagePNGRepresentation(myImage)

How do I convert imageData (i.e., NSData) back to a new UIImage?

回答1:

UIImage(data:imageData,scale:1.0) presuming the image's scale is 1.

回答2:

Thanks. Helped me a lot. Converted to Swift 3 and worked

To save: let data = UIImagePNGRepresentation(image)

To load: let image = UIImage(data: data)

回答3:

Use imageWithData: method, which gets translated to Swift as UIImage(data:)

let image : UIImage = UIImage(data: imageData)

回答4:

Now in Swift 4.2 you can use pngData() new instance method of UIImage to get the data from the image

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

回答5:

To save as data:

From StoryBoard, if you want to save "image" data on the imageView of MainStoryBoard, following codes will work.

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

To load "image" to imageView: Look at exclamation point "!", "?" closely whether that is quite same as this one.

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

"NSData" type is converted into "Data" type automatically during this process.

回答6:

For safe execution of code, use if-let block with Data to prevent app crash & , as function UIImagePNGRepresentation returns an optional value.

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

Note: Data is Swift 3+ class. Use Data instead of NSData with Swift 3+

Generic image operations (like png & jpg both):

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...
     }
}

By using extension:

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...
     }
}

回答7:

Image to Data:-

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

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

Data to Image:-

let image = UIImage(data: pngData)