UIImageJPEGRepresentation占用巨大的内存
我试图找出这个问题，但做了每一件事情后，我发现在操作系统或谷歌失败。 问题是，当我使用UIImageJPEGRepresentation或UIImagePNGRepresentation将UIImage转换为NSData它将内存大小增加到30Mb（相信我或不）。
这是我的代码
myImage= image; LoginSinglton*loginObj = [LoginSinglton sharedInstance]; NSError *error; NSData *pngData = UIImageJPEGRepresentation(image, scaleValue); //scaleVale is 1. NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsPath = [paths objectAtIndex:0]; //Get the docs directory self.imageCurrentDateAndTime =[self getTimeAndDate]; self.filePathAndDirectory = [documentsPath stringByAppendingPathComponent:@"Photos Dir"]; NSLog(@"Documents path %@",self.filePathAndDirectory); if (![[NSFileManager defaultManager] createDirectoryAtPath:self.filePathAndDirectory withIntermediateDirectories:NO attributes:nil error:&error]) { NSLog(@"Create directory error: %@", error); } self.imageName= [NSString stringWithFormat:@"photo-%@-%@.jpg",loginObj.userWebID,self.imageCurrentDateAndTime]; NSString *filePath = [self.filePathAndDirectory stringByAppendingPathComponent:self.imageName]; [pngData writeToFile:filePath atomically:YES]; //Write the file [self writeImageThumbnailToFolder:image]; [self writeImageHomeViewThumbnailToFolder:image];
我也试过以下解决scheme以及UIImageJPEGRepresentation – 内存释放问题
1-使用@autoreleasepool
2-完成pngData =零;
但仍然面临着这个记忆问题。
编辑我想我不能传达我的问题。 如果UIImageJPEGRepresentation占用了大量的内存，那么UIImageJPEGRepresentation ， 但是在保存图像之后内存应该回到它之前的位置。 希望这会帮助你详细。
使用小于1的scaleValue 。即使是0.9，也会极大地减less内存占用，并减less质量损失。
尝试这个：
UIGraphicsBeginImageContext(newSize); [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)]; UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();
如果没有得到您的期望的解决scheme，也不用担心这个问题：
UIImage *small = [UIImage imageWithCGImage:original.CGImage scale:0.25 orientation:original.imageOrientation];
在此处获取示例应用程序表单以编辑图像或比例： http : //mattgemmell.com/2010/07/05/mgimageutilities/
使用最小内存resize尝试使用CoreGraphics
所以回答 @Mina纳比勒，看到更多细节的完整答案
#import <ImageIO/ImageIO.h> -(UIImage*) resizedImageToRect:(CGRect) thumbRect { CGImageRef imageRef = [inImage CGImage]; CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef); if (alphaInfo == kCGImageAlphaNone) alphaInfo = kCGImageAlphaNoneSkipLast; // Build a bitmap context that's the size of the thumbRect CGContextRef bitmap = CGBitmapContextCreate( NULL, thumbRect.size.width, // width thumbRect.size.height, // height CGImageGetBitsPerComponent(imageRef), // really needs to always be 8 4 * thumbRect.size.width, // rowbytes CGImageGetColorSpace(imageRef), alphaInfo ); // Draw into the context, this scales the image CGContextDrawImage(bitmap, thumbRect, imageRef); // Get an image from the context and a UIImage CGImageRef ref = CGBitmapContextCreateImage(bitmap); UIImage* result = [UIImage imageWithCGImage:ref]; CGContextRelease(bitmap); // ok if NULL CGImageRelease(ref); return result; }