ios에서 이미지 압축 방법 요약

 
  
 - (UIImage*)scaleFromImage:(UIImage*)image scaledToSize:(CGSize)newSize 
  
 { 
  
  CGSize imageSize = image.size; 
  
  CGFloat width = imageSize.width; 
  
  CGFloat height = imageSize.height; 
  
       
  
  if (width <= newSize.width && height <= newSize.height){ 
  
   return image; 
  
  } 
  
       
  
  if (width == 0 || height == 0){ 
  
   return image; 
  
  } 
  
       
  
  CGFloat widthFactor = newSize.width / width; 
  
  CGFloat heightFactor = newSize.height / height; 
  
  CGFloat scaleFactor = (widthFactor       
  
  CGFloat scaledWidth = width * scaleFactor; 
  
  CGFloat scaledHeight = height * scaleFactor; 
  
  CGSize targetSize = CGSizeMake(scaledWidth,scaledHeight); 
  
       
  
     UIGraphicsBeginImageContext(targetSize); 
  
     [image drawInRect:CGRectMake(0,0,scaledWidth,scaledHeight)]; 
  
     UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext(); 
  
     UIGraphicsEndImageContext(); 
  
     return newImage; 
  
 } 
  
 
 

 
  
 #import   
  
 @interface UIImage (UIImageExt)  
  
 - (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size;  
  
 - (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize;  
  
 @end  
  
 
 

 
  
 #import "UIImageExt.h"  
  
 @implementation UIImage (UIImageExt)  
  
 - (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size{  
  
     //     bitmap context  
  
     //               context  
  
     UIGraphicsBeginImageContext(size);  
  
     //            
  
     [img drawInRect:CGRectMake(0, 0, size.width, size.height)];  
  
     //    context               
  
     UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();  
  
     //     context     
  
     UIGraphicsEndImageContext();  
  
     //               
  
     return scaledImage;  
  
 }  
  
 - (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  
  
 
 

 
  
 -(UIImage *) imageCompressForWidth:(UIImage *)sourceImage targetWidth:(CGFloat)defineWidth 
  
 { 
  
     CGSize imageSize = sourceImage.size; 
  
     CGFloat width = imageSize.width; 
  
     CGFloat height = imageSize.height; 
  
     CGFloat targetWidth = defineWidth; 
  
     CGFloat targetHeight = (targetWidth / width) * height; 
  
     UIGraphicsBeginImageContext(CGSizeMake(targetWidth, targetHeight)); 
  
     [sourceImage drawInRect:CGRectMake(0,0,targetWidth,  targetHeight)]; 
  
     UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext(); 
  
     UIGraphicsEndImageContext(); 
  
     return newImage; 
  
 }