convert UIImage to NSData

Question

I am using this code in my app which will help me to send a image.

However, I have an image view with an image. I have no file in appbundle but have the image in my side. How can I change the below code ? Can anyone tell me how can I convert myimage to NSData ?

// Attach an image to the email
NSString *path = [[NSBundle mainBundle] pathForResource:@"rainy" ofType:@"jpg"];
NSData *myData = [NSData dataWithContentsOfFile:path];
[picker addAttachmentData:myData mimeType:@"image/jpeg" fileName:@"rainy"];

UIImageJPEGRepresentation,UIImagePNGRepresentation both return nsdata of the image..... — Himanshu Agnihotri, Oct 16 '12 at 14:35

score 289 · Accepted Answer · edited May 10 '19 at 17:02

289

Try one of the following, depending on your image format:

UIImageJPEGRepresentation

Returns the data for the specified image in JPEG format.

NSData * UIImageJPEGRepresentation (
   UIImage *image,
   CGFloat compressionQuality
);

UIImagePNGRepresentation

Returns the data for the specified image in PNG format

NSData * UIImagePNGRepresentation (
   UIImage *image
);

Here the docs.

EDIT:

if you want to access the raw bytes that make up the UIImage, you could use this approach:

CGDataProviderRef provider = CGImageGetDataProvider(image.CGImage);
NSData* data = (id)CFBridgingRelease(CGDataProviderCopyData(provider));
const uint8_t* bytes = [data bytes];

This will give you the low-level representation of the image RGB pixels. (Omit the CFBridgingRelease bit if you are not using ARC).

edited May 10 '19 at 17:02

Cœur

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answered Jun 25 '11 at 09:26

sergio

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9

Is there a way to just get the data in whatever format it is already in? – devios1 Sep 14 '13 at 18:19
1

Xcode suggests me to use `(id)CFBridgingRelease(CGDataProviderCopyData(provider))` to take the ownership of `CDataRef` returned by `CGDataProviderCopyData` in ARC. – mostruash Jan 17 '14 at 12:42
1

@mostruash: thanks, I have modified my answer to take into account your suggestion. – sergio Jan 17 '14 at 14:52
@sergio I'm not experienced with non-ARC Obj-C and I wonder if releasing `data` would be enough or if there would still be a memory leak. – mostruash Jan 17 '14 at 15:15
@mostruash: in non-ARC case, there is no concept of ownership; the programmer should ensure that each object be released for any retain it received. In the present case, by releasing `data` you would ensure the object is properly deallocated: `CGDataProviderCopyData` gives you a retain count of `1`; be releasing the object, you make it to be dealloc-ed. – sergio Jan 17 '14 at 15:48
Note that imageFlags (like imageOrientation) get lost when using UIImagePNGRepresentation. That's why UIImageJPEGRepresentation is preferred – Yony Nov 01 '14 at 07:34
1

This won't help. The property CIImage is only set if it was initialized with imageWithCIImage:. Also this isn't directly the used data but rather another image representation object. – King-Wizard Mar 18 '15 at 09:45

score 166 · Answer 2 · edited Feb 27 '13 at 06:14

166

NSData *imageData = UIImagePNGRepresentation(myImage.image);

edited Feb 27 '13 at 06:14

Renjith

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answered May 22 '12 at 05:57

Radix

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I am using this line but this is very slow – user2128531 Mar 20 '13 at 11:03
5

Note that imageFlags (like imageOrientation) get lost when using UIImagePNGRepresentation. That's why UIImageJPEGRepresentation is preferred. – Yony Nov 01 '14 at 07:34

score 26 · Answer 3 · edited May 01 '17 at 05:12

If you have an image inside a UIImageView , e.g. "myImageView", you can do the following:

Convert your image using UIImageJPEGRepresentation() or UIImagePNGRepresentation() like this:

NSData *data = UIImagePNGRepresentation(myImageView.image);
//or
NSData *data = UIImageJPEGRepresentation(myImageView.image, 0.8);
//The float param (0.8 in this example) is the compression quality 
//expressed as a value from 0.0 to 1.0, where 1.0 represents 
//the least compression (or best quality).

You can also put this code inside a GCD block and execute in another thread, showing an UIActivityIndicatorView during the process ...

//*code to show a loading view here*

dispatch_queue_t myQueue = dispatch_queue_create("com.my.queue", DISPATCH_QUEUE_SERIAL);

dispatch_async(myQueue, ^{ 

    NSData *data = UIImagePNGRepresentation(myImageView.image);
    //some code....

    dispatch_async( dispatch_get_main_queue(), ^{
        //*code to hide the loading view here*
    });
});

score 24 · Answer 4 · edited Jun 09 '16 at 14:52

24

Create the reference of image....

UIImage *rainyImage = [UIImage imageNamed:@"rainy.jpg"];

displaying image in image view... imagedisplay is reference of imageview:

imagedisplay.image = rainyImage;

convert it into NSData by passing UIImage reference and provide compression quality in float values:

NSData *imgData = UIImageJPEGRepresentation(rainyImage, 0.9);

edited Jun 09 '16 at 14:52

ChikabuZ

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answered Nov 15 '13 at 12:04

Jemythehigh

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score 2 · Answer 5 · answered Jul 15 '17 at 14:53

2

Solution in Swift 4

extension UIImage {
    var data : Data? {
      return cgImage?.dataProvider?.data as Data?
    }
}

answered Jul 15 '17 at 14:53

Charlton Provatas

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How is the `cgImage.dataProvider` data encoded? It seems to be different from the data of `UIImagePNGRepresentation` and `UIImageJPEGRepresentation` because it cannot be used to create an image like so `UIImage(data: imageData)`. – Manuel Nov 17 '17 at 11:56
@Manuel Not sure. I just converted the syntax from Sergio 's answer. Sergio would probably know better. – Charlton Provatas Nov 17 '17 at 12:52
@Manuel I'm assuming because it's using CoreGraphics API it's giving a lower-level data representation of the image than what `UIImageJPEGRepresentation` provides. But I believe this solution preserves the original encoding format that the image was in and doesn't re-encode it. – Charlton Provatas Nov 17 '17 at 12:55

score 1 · Answer 6 · answered Oct 27 '17 at 08:50

Use if-let block with Data to prevent app crash & safe execution of code, 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(img)
    }

    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...
     }
}

Jayesh Mardiya · Answer 7 · 2015-12-10T07:29:29.233

0

- (void) imageConvert
{
     UIImage *snapshot = self.myImageView.image;
     [self encodeImageToBase64String:snapshot];
}    


call this method for image convert in base 64 
    -(NSString *)encodeImageToBase64String:(UIImage *)image
    {
        return [UIImagePNGRepresentation(image) base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
    }

edited Dec 10 '15 at 07:29

answered Dec 10 '15 at 07:23

Jayesh Mardiya

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convert UIImage to NSData

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