对图片进行压缩
dataImage = UIImageJPEGRepresentation(imageReadyPost, 1.0);
NSUInteger sizeOrigin = [dataImage length];
NSUInteger sizesizeOriginKB = sizeOrigin / 1024;

// 图片大于500k要先进行压缩

if (sizesizeOriginKB > 500)

{

float a = 500.00000;
float b = (float)sizesizeOriginKB;
float q = sqrt(a/b);
CGSize sizeImage = [imageReadyPost size];
CGFloat iwidthSmall = sizeImage.width * q;
CGFloat iheightSmall = sizeImage.height * q;
CGSize itemSizeSmall = CGSizeMake(iwidthSmall, iheightSmall);
UIGraphicsBeginImageContext(itemSizeSmall);
CGRect imageRectSmall = CGRectMake(0.0f, 0.0f, itemSizeSmall.width, itemSizeSmall.height);
[imageReadyPost drawInRect:imageRectSmall];
UIImage *SmallImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSData *dataImageSend = UIImageJPEGRepresentation(SmallImage, 1.0);

dataImage = dataImageSend;

｝

最后把dataImage发送出去