Use this method to resize your image:
+(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;
}