iOS中等比压缩截图代码

将一幅图片按着需要的尺寸进行等比的压缩和放大，最后再截取需要尺寸部分，不知道说清楚没，反正就那意思吧！

+(UIImage *)compressImageWith:(UIImage *)image width:(float)width height:(float)height

{

float imageWidth = image.size.width;

float imageHeight = image.size.height;

float widthScale = imageWidth /width;

float heightScale = imageHeight /height;

// 创建一个bitmap的context

// 并把它设置成为当前正在使用的context

UIGraphicsBeginImageContext(CGSizeMake(width, height));

if (widthScale > heightScale) {

[image drawInRect:CGRectMake(0, 0, imageWidth /heightScale , height)];

}

else {

[image drawInRect:CGRectMake(0, 0, width , imageHeight /widthScale)];

}

// 从当前context中创建一个改变大小后的图片

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

[newImage retain];

// 使当前的context出堆栈

UIGraphicsEndImageContext();

return newImage;

}