解码 NSString 中的 Base-64 编码 PNG

我有一些NSData它是 Base-64 编码的，我想解码它，我看到了一个如下所示的示例

NSData* myPNGData = [xmlString dataUsingEncoding:NSUTF8StringEncoding];

[Base64 initialize];
NSData *data = [Base64 decode:img];
cell.image.image = [UIImage imageWithData:myPNGData];

然而，这给我带来了很多错误，我想知道该怎么做才能让它发挥作用。我是否需要将某种类型的文件导入到我的项目中，或者是否必须包含框架？

这些是我得到的错误

Use of undeclared identifier 'Base64'
Use of undeclared identifier 'Base64'
Use of undeclared identifier 'cell'

我到处都看过，但不知道该怎么做。

您可以将 Base64 编码的字符串解码为NSData:

-(NSData *)dataFromBase64EncodedString:(NSString *)string{
    if (string.length > 0) {

        //the iPhone has base 64 decoding built in but not obviously. The trick is to
        //create a data url that's base 64 encoded and ask an NSData to load it.
        NSString *data64URLString = [NSString stringWithFormat:@"data:;base64,%@", string];
        NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:data64URLString]];
        return data;
    }
    return nil;
}

使用上述方法从 Base64 字符串获取图像的示例：

-(void)imageFromBase64EncodedString{

    NSString *string = @"";  // replace with encocded string
    NSData *imageData = [self dataFromBase64EncodedString:string];
    UIImage *myImage = [UIImage imageWithData:imageData];

    // do something with image
}