将任何数据类型转换为NSData并再次返回 [英] Convert any Data Type into NSData and back again

问题描述

我正在开发一个应用程式，您可以透过「多重连接」将文字，图片或联络人传送至其他装置。然后它将保存在第二个设备的核心数据中。

I'm working on an app where you can send either a text, image or a contact over Multipeer Connectivity to another device. It will then save in the second device's Core Data.

我所做的是以NSDictionary的形式发送数据并将其重新转换。所以我留在接收设备上的NSDictionary。那么，我可以将对象的@objectData的键保存到Core Data？

What I do is send the data over as an NSDictionary and convert it back again. So I am left with an NSDictionary on the receiving device. How then, can I save the object for the key of @"objectData" to Core Data?

我想要使用NSString，UIImage& ABPerson。

I'd like it to work with NSString, UIImage & ABPerson.

    // Create a new object in the managed object context.
    Received *receivedData = [NSEntityDescription insertNewObjectForEntityForName:@"Received" inManagedObjectContext:self.managedObjectContext];
    // Assign the properties based on what was input in the textfields.

    // Check what type it is
    NSString *dataType = [dictionary objectForKey:@"type"];
    receivedData.type =  dataType;

    // Determine what type of data was passed over...

    if ([dataType isEqualToString:@"Photo"])
    {
        receivedData.object = UIImageJPEGRepresentation([dictionary 
                                                         objectForKey:@"object"], 0.5f);

        NSLog(@"A photo saved in core data");
    }
    else  
    { 

      //receivedData.object = [NSKeyedArchiver archivedDataWithRootObject:[dictionary objectForKey:@"object"]];
      receivedData.object = [[dictionary objectForKey:@"object"] dataUsingEncoding:NSUTF8StringEncoding];

    }

    // Save the managed object context.
    NSError *error = nil;
    [self.managedObjectContext save:&error];

我不是特别想做if，else if语句来决定如何转换它的核心数据，因为它将在我显示数据时重复。呃，我可以吗？我目前得到的NSKeyedArchiver类型的错误，我不确定为什么，因此它被注释掉。

I don't particularly want to do the if, else if statements to determine how to convert it core data as it would then be repeated when I display the data. Hoe else can I do it? I am currently getting errors with the NSKeyedArchiver type which I am unsure why and hence it is commented out.

任何帮助将非常感激！

推荐答案

尝试此链接以了解其工作原理

您可以为符合 NSCoding的任何对象获取NSData （或 NSSecureCoding ）协议：

You can get NSData for any object conforming to the NSCoding (or NSSecureCoding) protocol:

NSData *data=[NSKeyedArchiver archivedDataWithRootObject:yourObject];

此行从 NSData / p>

this line creates an object from NSData

TestClass *objTest=[NSKeyedUnarchiver unarchiveObjectWithData:yourData];

UIImage NSString 符合 NSCoding ，但对于 ABPerson ，您需要使用 vCardRepresentation 其返回 NSData 。

UIImage and NSString conform to NSCoding, but for ABPerson you'll need to use the vCardRepresentation which returns NSData.

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