上传图片到服务器 对图片进行压缩

iPhone拍照 图片还是有点大    对图片不进行处理  上传到服务器  经查询一张图片大小约1.8M左右   

因为一次性可能要上传几十张图片   1.8M一张图片   这明显有点大了

忘记从哪位网友那看来的,不过我项目中使用了，经过处理后图片一张大约200k吧

图片压缩代码   

.h

#import <UIKit/UIKit.h>

@interface UIImage (lxy)

- (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size;

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

.m
#import "UIImage+lxy.h"

@implementation UIImage (lxy)

- (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size{
// 创建一个bitmap的context
// 并把它设置成为当前正在使用的context
UIGraphicsBeginImageContext(size);
// 绘制改变大小的图片
[img drawInRect:CGRectMake(0, 0, size.width, size.height)];
// 从当前context中创建一个改变大小后的图片
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
// 使当前的context出堆栈
UIGraphicsEndImageContext();
// 返回新的改变大小后的图片
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;
}


我在项目中的使用方法

#pragma mark---ImagePickerControllerDelegate---
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info{

UIImage *image = [info valueForKey:UIImagePickerControllerOriginalImage];
//通过判断picker的sourceType，如果是拍照则保存到相册去
if (picker.sourceType == UIImagePickerControllerSourceTypeCamera) {
UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}

CGSize size = image.size;
if (size.width > 800) {

size.height = size.height*800/size.width;
size.width = 800;
} else if (size.width < 500) {
size.width = 500;
size.height = size.height;
}

image = [[[UIImage alloc]init]scaleToSize:image size:size];

SafeCheck *model = _dataArray[subNumber];
[model.imageList addObject:image];
_dataArray[subNumber] = model;

NSString *title = model.imageList.count?[NSString stringWithFormat:@"已拍:%ld",(long)model.imageList.count]:@"拍照";
[((SafeCheckCell *)[_mainTBV cellForRowAtIndexPath:[NSIndexPath indexPathForRow:subNumber inSection:0]]).photoBtn setTitle:title forState:UIControlStateNormal];

[picker dismissViewControllerAnimated:NO completion:nil];

}

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {

}