调整图片的尺寸

头文件：

 

#import <Foundation/Foundation.h>

@interface UIImage (Resize)

- (UIImage *)transformWidth:(CGFloat)width height:(CGFloat)height;

@end

 

实现文件：

 

#import "ImageResize.h"

@implementation UIImage (Resize)

- (UIImage *)transformWidth:(CGFloat)width height:(CGFloat)height {	
	CGFloat destW = width;
	CGFloat destH = height;
	CGFloat sourceW = width;
	CGFloat sourceH = height;
	
	CGImageRef imageRef = self.CGImage;
	CGContextRef bitmap = CGBitmapContextCreate(NULL, destW, destH,
																							CGImageGetBitsPerComponent(imageRef), 
																							4 * destW, CGImageGetColorSpace(imageRef),
																							(kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst));
	
	CGContextDrawImage(bitmap, CGRectMake(0, 0, sourceW, sourceH), imageRef);
	
	CGImageRef ref = CGBitmapContextCreateImage(bitmap);
	UIImage *result = [UIImage imageWithCGImage:ref];
	CGContextRelease(bitmap);
	CGImageRelease(ref);
	
	return result;
}

@end

 

示例：

 

NSString *path = [[NSBundle mainBundle] pathForResource:@"image" ofType:@"png"];
UIImage *image = [[UIImage alloc] initWithContentsOfFile:path];
image = [image transformWidth:100.f height:100.f];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
[image release];
[self.view addSubview:imageView];
[imageView release];