将UIImage转换为NSData并返回UIImage [英] convert UIImage to NSData and back to UIImage

问题描述

我必须从数据库中填充表格单元格，并且图像在设备上。
我将该图像存储在 imageDataObject 中，如何将 UIImage 转换为 NSData的。
请建议，我尝试了很多解决方案，但它没有将 NSData 转换回 UIImage 。

I have to populate table cell from database and images are on device. I've to store that image in imageDataObject, how to convert that UIImage to NSData. Please suggest, I tried many solution but it's not converting back that NSData to UIImage.

    cell.textLabel.text = [[offlineImageListArray objectAtIndex:indexPath.row] imageName];
    UIImage *thumbnail = [self retrieveImageFromDevice:[[offlineImageListArray objectAtIndex:indexPath.row] imageName]];
    NSData* data = ??????????;
    ImageData *imageDataObject = [[ImageData alloc] initWithImageId:[[offlineImageListArray objectAtIndex:indexPath.row]imageId] 
    imageName:[[offlineImageListArray objectAtIndex:indexPath.row] imageName] imageData:data];
    [imagesArray addObject:imageDataObject];

推荐答案

转换 UIImage 到 NSData ，使用 UIImageJPEGRepresentation（UIImage * image，CGFloat compressionQuality）或 UIImagePNGRepresentation（UIImage * image）

将 NSData 转换为 UIImage ，使用 [UIImage imageWithData：imageData]

所以你的例子可能如下所示：

So your example could look like this:

cell.textLabel.text = [[offlineImageListArray objectAtIndex:indexPath.row] imageName];
UIImage *thumbnail = [self retrieveImageFromDevice:[[offlineImageListArray objectAtIndex:indexPath.row] imageName]];
NSData* data = UIImagePNGRepresentation(thumbnail);
ImageData *imageDataObject = [[ImageData alloc] initWithImageId:[[offlineImageListArray objectAtIndex:indexPath.row]imageId] imageName:[[offlineImageListArray objectAtIndex:indexPath.row] imageName] imageData:data];
[imagesArray addObject:imageDataObject];

参考文献： https://developer.apple.com/LIBRARY/IOS/documentation/UIKit/Reference/UIKitFunctionReference/Reference/reference.html
https://developer.apple.com/Library/ios/documentation/ UIKit / Reference / UIImage_Class / Reference / Reference.html

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