ios压缩图片

/**

*  压缩图片到指定文件大小

*

*  @param image 目标图片

*  @param size  目标大小（最大值）

*

*  @return 返回的图片文件

*/

- (NSData *)compressOriginalImage:(UIImage *)image toMaxDataSizeKBytes:(CGFloat)size{

NSData * data = UIImageJPEGRepresentation(image, 1.0);

CGFloat dataKBytes = data.length/1000.0;

CGFloat maxQuality = 0.9f;

CGFloat lastData = dataKBytes;

while (dataKBytes > size && maxQuality > 0.01f) {

maxQuality = maxQuality - 0.01f;

data = UIImageJPEGRepresentation(image, maxQuality);

dataKBytes = data.length / 1000.0;

if (lastData == dataKBytes) {

break;

}else{

lastData = dataKBytes;

}

}

return data;

}

///原图压缩

-(NSData *)compressOriginalImage:(UIImage *)image

withRatio:(float)ratio

{

int largePicH = (int)image.size.height/ratio;

int largePicW = (int)image.size.width/ratio;

CGSize newSize = CGSizeMake(largePicW, largePicH);

UIGraphicsBeginImageContext(newSize);

[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

//调整大小

NSData *imageData;

imageData = UIImageJPEGRepresentation(newImage, 0.5);

return imageData;

}

///获取压缩倍数

- (float)resetSizeOfImageData:(UIImage *)img

withLargePicH:(int)largePicH

withLargePicW:(int)largePicW

{

float inSampleSize = 1.0f;

int height = img.size.height;

int width = img.size.width;

if ( height > largePicH || width > largePicW) {

//swap value, make width is bigger than height

if(height > width){

int swapValue = height;

height = width;

width = swapValue;

}

// Calculate ratios of height and width to requested height and

// width

float heightRatio =  (float)height/largePicH;

float widthRatio = (float)width/largePicW ;

inSampleSize = heightRatio > widthRatio ? heightRatio : widthRatio;

}

return inSampleSize;

}

///缩略图压缩

-(NSData *)imageCompressForSize:(UIImage *)sourceImage targetSize:(CGSize)size{

UIImage *newImage = nil;

CGSize imageSize = sourceImage.size;

CGFloat width = imageSize.width;

CGFloat height = imageSize.height;

CGFloat targetWidth = size.width;

CGFloat targetHeight = size.height;

CGFloat scaleFactor = 0.0;

CGFloat scaledWidth = targetWidth;

CGFloat scaledHeight = targetHeight;

CGPoint thumbnailPoint = CGPointMake(0.0, 0.0);

if(CGSizeEqualToSize(imageSize, size) == NO){

CGFloat widthFactor = targetWidth / width;

CGFloat heightFactor = targetHeight / height;

if(widthFactor > heightFactor){

scaleFactor = widthFactor;

}else{

scaleFactor = heightFactor;

}

scaledWidth = width * scaleFactor;

scaledHeight = height * scaleFactor;

if(widthFactor > heightFactor){

thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;

}else if(widthFactor < heightFactor){

thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;

}

}

UIGraphicsBeginImageContextWithOptions(size, NO, 3.0);

CGRect thumbnailRect = CGRectZero;

thumbnailRect.origin = thumbnailPoint;

thumbnailRect.size.width = scaledWidth;

thumbnailRect.size.height = scaledHeight;

[sourceImage drawInRect:thumbnailRect];

newImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

//调整大小

NSData *imageData;

imageData = UIImageJPEGRepresentation(newImage,0.3);

return imageData;

}