Download an Image and Save it as PNG or JPEG in iPhone SDK

Download an Image and Save it as PNG or JPEG in iPhone SDK

On 04.05.10, In iphone, iphone development, objective-c, by kiichi

Here is a quick example to save an image as JPEG or PNG. In this tutorial, I’m getting the image from the Internet then I’m saving it as JPEG and PNG.

Key points:

NSData to retrieve the image from the URL
NSDocumentDirectory to find Document folder’s Path
UIImagePNGRepresentation to save it as PNG
UIImageJPEGRepresentation to save it as JPEG

	NSLog(@"Downloading...");
	// Get an image from the URL below
	UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://www.objectgraph.com/images/og_logo.png"]]];
 
	NSLog(@"%f,%f",image.size.width,image.size.height);
 
	// Let's save the file into Document folder.
	// You can also change this to your desktop for testing. (e.g. /Users/kiichi/Desktop/)
	// NSString *deskTopDir = @"/Users/kiichi/Desktop";
 
	NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
 
	// If you go to the folder below, you will find those pictures
	NSLog(@"%@",docDir);
 
	NSLog(@"saving png");
	NSString *pngFilePath = [NSString stringWithFormat:@"%@/test.png",docDir];
	NSData *data1 = [NSData dataWithData:UIImagePNGRepresentation(image)];
	[data1 writeToFile:pngFilePath atomically:YES];
 
	NSLog(@"saving jpeg");
	NSString *jpegFilePath = [NSString stringWithFormat:@"%@/test.jpeg",docDir];
	NSData *data2 = [NSData dataWithData:UIImageJPEGRepresentation(image, 1.0f)];//1.0f = 100% quality
	[data2 writeToFile:jpegFilePath atomically:YES];
 
	NSLog(@"saving image done");
 
	[image release];