IOS 改变图片尺寸和大小方法

一、改变size 

- (UIImage *)image:(UIImage*)image byScalingToSize:(CGSize)targetSize { UIImage *sourceImage = image; UIImage *newImage = nil; UIGraphicsBeginImageContext(targetSize); CGRect thumbnailRect = CGRectZero; thumbnailRect.origin = CGPointZero; thumbnailRect.size.width = targetSize.width; thumbnailRect.size.height = targetSize.height; [sourceImage drawInRect:thumbnailRect]; newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return newImage ; }

二、改变字节(多用于上传至服务器时) 

UIKIT_EXTERN NSData *UIImagePNGRepresentation(UIImage *image); UIKIT_EXTERN NSData *UIImageJPEGRepresentation(UIImage *image, CGFloat compressionQuality);