IOS - 下载图像从Parse.com后端 [英] IOS - Downloading Images From Parse.com Backend

问题描述

ORI有一个应用程序是一致的，从解析后端下载大的图像。在Android中，你可以下载图像，使用他们的URI流和特定的尺寸大小设置为我要下载的位图。通常这是使用BitmapFactory库完成，让我可以下载一个位图，这是一个缩小尺寸，从长期的加载时间救了我的应用程序。是否有一个等价的IOS平台上的这种方法吗？这是我目前在做什么，但是当我下载15全尺寸的图像，我得到了大量的加载时间：

orI have an app that is consistently downloading large images from a parse back-end. In android you can download the images as streams using their URI's and set a specific dimension size to the bitmap that I want to download. Usually this is done using the BitmapFactory libraries and allows me to download a bitmap that's of a scaled down size, saving my app from long loading times. Is there an equivalency to this method on the IOS platform? This is what I am currently doing, but when I download 15 full sized images I get a large amount of load time:

//where photoQuery is a Parse.com database query that returns the photo as the first object
PFObject *photoObject = [photoQuery getFirstObject];
PFFile *photoFile = (PFFile *)[photoObject objectForKey:@"fullSizedImage"];

UIImage *fullImage = [UIImage imageWithData:photoFile.getData];

是否类似BitmapFactory或这种常见的Andr​​oid设计模式IOS支持的东西吗？

Does IOS support something similar to BitmapFactory or this common android design pattern?

推荐答案

PFFile 有一个名为法 - getDataInBackgroundWithBlock：。可以使用这样的：

PFFile has a method called – getDataInBackgroundWithBlock:. Which can be used like this:

[photoFile getDataInBackgroundWithBlock:^(NSData *data, NSError *error) {
    if(!error) {
        [imageView setImage:[UIImage imageWithData:data];
    }
}

或者你可以使用一个叫做另一种方法 - getDataStreamInBackgroundWithBlock：。它是如上所述一个相似的。所不同的是该块的第一个参数是一个 NSInputStream

Or you can use another method called - getDataStreamInBackgroundWithBlock:. It is similar as the one above. The difference is the first parameter of the block is a NSInputStream

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