Combine two UIImages

CombineImages.m

// Let’s say we have two images we want to combine; say an image of a person that we want to overlay an image of a funny hat on to. 
// Here are the two UIImages:

UIImage *personImage = [UIImage imageNamed:@"person.jpg"];
UIImage *hatImage = [UIImage imageNamed:@"hat.png];

// In this case we want the resultant image to be that same size as the personImage. 
// Let’s get the size that we want for the final image:

CGSize finalSize = [personImage size];

// Also get the size of the hat image which is probably much smaller:

CGSize hatSize = [hatImage size];

//Now we need to create a graphics context in which we will do our drawing:

UIGraphicsBeginImageContext(finalSize);

// The graphics context is kind of like out piece of paper that we will draw to. 
// The first thing we want to draw on it is the photo of the person:

[personImage drawInRect:CGRectMake(0,0,finalSize.width,finalSize.height)];

// Now we draw the hat at the position that we want it to be on top of the other image.

[hatImage drawInRect:CGRectMake(HAT_X_POS,HAT_Y_POS,hatSize.width,hatSize.height)];

// Next we create the new UIImage with:

UIImage *newImage = [UIGraphicsGetImageFromCurrentImageContext();

// Finally we need to clean up and close the context as we no longer need it:

UIGraphicsEndImageContext();

// That is all there is to it.