How do I save a UIImage to a file?

Question

If I have a UIImage from an imagePicker, how can I save it to a subfolder in the documents directory?

Answer 1

The above are useful, but they don't answer your question of how to save in a subdirectory or get the image from a UIImagePicker.

First, you must specify that your controller implements image picker's delegate, in either .m or .h code file, such as:

@interface CameraViewController () 

@end

Then you implement the delegate's imagePickerController:didFinishPickingMediaWithInfo: method, which is where you can get the photograph from the image picker and save it (of course, you may have another class/object that handles the saving, but I'll just show the code inside the method):

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    // get the captured image
    UIImage *image = (UIImage *)info[UIImagePickerControllerOriginalImage];


    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *imageSubdirectory = [documentsDirectory stringByAppendingPathComponent:@"MySubfolderName"];

    NSString *filePath = [imageSubdirectory stringByAppendingPathComponent:@"MyImageName.png"];

    // Convert UIImage object into NSData (a wrapper for a stream of bytes) formatted according to PNG spec
    NSData *imageData = UIImagePNGRepresentation(image); 
    [imageData writeToFile:filePath atomically:YES];
}

If you want to save as JPEG image, the last 3 lines would be:

NSString *filePath = [imageSubdirectory stringByAppendingPathComponent:@"MyImageName.jpg"];

// Convert UIImage object into NSData (a wrapper for a stream of bytes) formatted according to JPG spec
NSData *imageData = UIImageJPEGRepresentation(image, 0.85f); // quality level 85%
[imageData writeToFile:filePath atomically:YES];