SDWebImage加载高分辨率图片内存暴涨问题

目前使用的SDWebImage版本为4.3.3 ，其他版本自测～

SDWebImageImageIOCoder.m

// 添加方法

-(UIImage *)compressImageWith:(NSData *)imageDD
{
    UIImage *image = [UIImage imageWithData:imageDD];
    float imageWidth = image.size.width;
    float imageHeight = image.size.height;
//这里的width看自己需求，如果嫌图片模糊就加大点，我这里屏幕宽度*2.5刚好达到需求
    float width = [UIScreen mainScreen].bounds.size.width * 2.5; 
    if (imageWidth < width) {
        width = imageWidth;
    }
    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;
    
}

修改 - (UIImage *)decodedImageWithData:(NSData *)data 方法

- (UIImage *)decodedImageWithData:(NSData *)data {
    if (!data) {
        return nil;
    }
    
    //UIImage *image = [[UIImage alloc] initWithData:data];
    UIImage *image = [self compressImageWith:data];
    
#if SD_MAC
    return image;
#else
    if (!image) {
        return nil;
    }
    
    UIImageOrientation orientation = [[self class] sd_imageOrientationFromImageData:data];
    if (orientation != UIImageOrientationUp) {
        image = [[UIImage alloc] initWithCGImage:image.CGImage scale:image.scale orientation:orientation];
    }
    
    return image;
#endif
}