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
– Himanshu Agnihotri, Commented Oct 16, 2012 at 14:35

Cœur · Accepted Answer · 2019-05-10 17:02:27Z

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).

Is there a way to just get the data in whatever format it is already in?
Xcode suggests me to use (id)CFBridgingRelease(CGDataProviderCopyData(provider)) to take the ownership of CDataRef returned by CGDataProviderCopyData in ARC.
@mostruash: thanks, I have modified my answer to take into account your suggestion.
@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.
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.

Renjith · Accepted Answer · 2013-02-27 06:14:46Z

168

NSData *imageData = UIImagePNGRepresentation(myImage.image);

edited Feb 27, 2013 at 6:14

Renjith

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answered May 22, 2012 at 5:57

Radix

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2 Comments

user2128531 Over a year ago

I am using this line but this is very slow

Yony Over a year ago

Note that imageFlags (like imageOrientation) get lost when using UIImagePNGRepresentation. That's why UIImageJPEGRepresentation is preferred.

Efren · Accepted Answer · 2017-05-01 05:12:06Z

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* }); });

ChikabuZ · Accepted Answer · 2016-06-09 14:52:38Z

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);

Charlton P · Accepted Answer · 2017-07-15 14:53:11Z

2

Solution in Swift 4

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

answered Jul 15, 2017 at 14:53

Charlton P

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3 Comments

Manuel Over a year ago

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).

Charlton P Over a year ago

@Manuel Not sure. I just converted the syntax from Sergio 's answer. Sergio would probably know better.

Charlton P Over a year ago

@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.

Krunal · Accepted Answer · 2017-10-27 08:50:06Z

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 · Accepted Answer · 2015-12-10 07:29:29Z

- (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]; }

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