//UIImageExtras.h

@interface UIImage (Extras)

- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize;

@end



//UIImageExtras.m

#import "UIImageExtras.h"


@implementation UIImage (Extras)

#pragma mark -
#pragma mark Scale and crop image

- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
	UIImage *sourceImage = self;
	UIImage *newImage = nil;        
	CGSize imageSize = sourceImage.size;
	CGFloat width = imageSize.width;
	CGFloat height = imageSize.height;
	CGFloat targetWidth = targetSize.width;
	CGFloat targetHeight = targetSize.height;
	CGFloat scaleFactor = 0.0;
	CGFloat scaledWidth = targetWidth;
	CGFloat scaledHeight = targetHeight;
	CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
	
	if (CGSizeEqualToSize(imageSize, targetSize) == NO) 
	{
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;
		
        if (widthFactor > heightFactor) 
			scaleFactor = widthFactor; // scale to fit height
        else
			scaleFactor = heightFactor; // scale to fit width
        scaledWidth  = width * scaleFactor;
        scaledHeight = height * scaleFactor;
		
        // center the image
        if (widthFactor > heightFactor)
		{
			thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; 
		}
        else 
			if (widthFactor < heightFactor)
			{
				thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
			}
	}       
	
	UIGraphicsBeginImageContext(targetSize); // this will crop
	
	CGRect thumbnailRect = CGRectZero;
	thumbnailRect.origin = thumbnailPoint;
	thumbnailRect.size.width  = scaledWidth;
	thumbnailRect.size.height = scaledHeight;
	
	[sourceImage drawInRect:thumbnailRect];
	
	newImage = UIGraphicsGetImageFromCurrentImageContext();
	if(newImage == nil) 
        NSLog(@"could not scale image");
	
	//pop the context to get back to the default
	UIGraphicsEndImageContext();
	return newImage;
}

@end


//Using
#import "UIImageExtras.h"

croppedAndResizedImage = [originalImage imageByScalingAndCroppingForSize:CGSizeMake(500, 200)];

This code snippet helps you to resize and crop UIImage in your iOS app It's written by: csade