Utilizzare questo metodo per ridimensionare l'immagine:
+(UIImage *)imageResize :(UIImage*)img andResizeTo:(CGSize)newSize
{
CGFloat scale = [[UIScreen mainScreen]scale];
/*You can remove the below comment if you dont want to scale the image in retina device .Dont forget to comment UIGraphicsBeginImageContextWithOptions*/
//UIGraphicsBeginImageContext(newSize);
UIGraphicsBeginImageContextWithOptions(newSize, NO, scale);
[img drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
http://stackoverflow.com/questions/10491080/uiimage-resizing-not-working-properly/10491692 # 10491692 controlla questa fantastica risposta di Rob – pmk