UIImage vs NSImage: Drawing to an off screen image in iOS

Question

In mac osx (cocoa), It is very easy to make a blank image of a specific size and draw to it off screen:

NSImage* image = [[NSImage alloc] initWithSize:NSMakeSi         


        

Answer 1

Something like this:

UIGraphicsBeginImageContextWithOptions(mySize, NO, 0.0f);       
CGContextRef context = UIGraphicsGetCurrentContext();
UIGraphicsPushContext(context);

[myImage drawInRect:myImageRect];
[myText drawAtPoint:myOrigin withFont:myFont];

UIGraphicsPopContext();
UIImage *myNewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

Answer 2

You can do that as follows:

UIGraphicsBeginImageContext(CGSizeMake(64, 64));
//Drawing code here
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

Here is Apple's Graphics and Drawing reference.

Answer 3

CoreGraphics is needed here, as UIImage does not have high level functions like what you explained..

UIGraphicsBeginImageContext(CGSizeMake(64,64));

CGContextRef context = UIGraphicsGetCurrentContext();
// drawing code here (using context)

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();