SDWebImage 加载一些大的图片的时候导致程序崩溃

在  UIImage+MultiFormat这个类里面添加如下压缩方法，

+(UIImage *)compressImageWith:(UIImage *)image

{

float imageWidth = image.size.width;

float imageHeight = image.size.height;

float width = 640;

float height = image.size.height/(image.size.width/width);

float widthScale = imageWidth /width;

float heightScale = imageHeight /height;

// 创建一个bitmap的context

// 并把它设置成为当前正在使用的context

UIGraphicsBeginImageContext(CGSizeMake(width, height));

if (widthScale > heightScale) {

[image drawInRect:CGRectMake(0, 0, imageWidth /heightScale , height)];

}

else {

[image drawInRect:CGRectMake(0, 0, width , imageHeight /widthScale)];

}

// 从当前context中创建一个改变大小后的图片

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

// 使当前的context出堆栈

UIGraphicsEndImageContext();

return newImage;

}

再在上面箭头代码后面对图片进行压缩

1. + (UIImage *)sd_imageWithData:(NSData *)data {

   UIImage *image;

   NSString *imageContentType = [NSData sd_contentTypeForImageData:data];

   if ([imageContentType isEqualToString:@"image/gif"]) {

   image = [UIImage sd_animatedGIFWithData:data];

   }

   #ifdef SD_WEBP

   else if ([imageContentType isEqualToString:@"image/webp"])

   {

   image = [UIImage sd_imageWithWebPData:data];

   }

   #endif

   else {

   image = [[UIImage alloc] initWithData:data];

   if (data.length/1024 > 128) {

   image = [self compressImageWith:image];

   }

   UIImageOrientation orientation = [self sd_imageOrientationFromImageData:data];

   if (orientation != UIImageOrientationUp) {

   image = [UIImage imageWithCGImage:image.CGImage

   scale:image.scale

   orientation:orientation];

   }

   }

   return image;

   }

到了这里还需要进行最后一步。就是在SDWebImageDownloaderOperation的connectionDidFinishLoading方法里面的：

UIImage *image = [UIImage sd_imageWithData:self.imageData];

//将等比压缩过的image在赋在转成data赋给self.imageData
NSData *data = UIImageJPEGRepresentation(image, 1);
self.imageData = [NSMutableData dataWithData:data];

再配合    [[SDImageCache sharedImageCache] setValue:nil forKey:@"memCache"];（图片加载后使用）大功告成，亲测内存基本变化不大，自动释放也来得及。