//Deserialize each nil Parse property with NSNull
    //This is to prevent an NSInternalConsistencyException when trying to access them in the future
    for (NSString* key in [self dynamicProperties]) {
        if (![allKeys containsObject:key]) {
            self[key] = [NSNull null];
        }
    }

我建议你使用一个替代的NSCoding库.

@AaronBrager在4月22日的答案中建议一个替代图书馆.

更新：

由于替代库缺少对PFFile的支持,下面是您为PFFile实现NSCoding所需的更改的类别实现.简单地编译并添加PFFile NSCoding.m到您的项目.
此实现来自您使用的原始NSCoding库.

PFFile NSCoding.h

//
//  PFFile+NSCoding.h
//  UpdateZen
//
//  Created by Martin Rybak on 2/3/14.
//  Copyright (c) 2014 UpdateZen. All rights reserved.
//

#import <Parse/Parse.h>

@interface PFFile (NSCoding)

- (void)encodeWithCoder:(NSCoder*)encoder;
- (id)initWithCoder:(NSCoder*)aDecoder;

@end

PFFile NSCoding.m

//
//  PFFile+NSCoding.m
//  UpdateZen
//
//  Created by Martin Rybak on 2/3/14.
//  Copyright (c) 2014 UpdateZen. All rights reserved.
//

#import "PFFile+NSCoding.h"
#import <objc/runtime.h>

#define kPFFileName @"_name"
#define kPFFileIvars @"ivars"
#define kPFFileData @"data"

@implementation PFFile (NSCoding)

- (void)encodeWithCoder:(NSCoder*)encoder
{
    [encoder encodeObject:self.name forKey:kPFFileName];
    [encoder encodeObject:[self ivars] forKey:kPFFileIvars];
    if (self.isDataAvailable) {
        [encoder encodeObject:[self getData] forKey:kPFFileData];
    }
}

- (id)initWithCoder:(NSCoder*)aDecoder
{
    NSString* name = [aDecoder decodeObjectForKey:kPFFileName];
    NSDictionary* ivars = [aDecoder decodeObjectForKey:kPFFileIvars];
    NSData* data = [aDecoder decodeObjectForKey:kPFFileData];

    self = [PFFile fileWithName:name data:data];
    if (self) {
        for (NSString* key in [ivars allKeys]) {
            [self setValue:ivars[key] forKey:key];
        }
    }
    return self;
}

- (NSDictionary *)ivars
{
    NSMutableDictionary* dict = [[NSMutableDictionary alloc] init];
    unsigned int outCount;

    Ivar* ivars = class_copyIvarList([self class],&outCount);
    for (int i = 0; i < outCount; i++){
        Ivar ivar = ivars[i];
        NSString* ivarNameString = [NSString stringWithUTF8String:ivar_getName(ivar)];
        NSValue* value = [self valueForKey:ivarNameString];
        if (value) {
            [dict setValue:value forKey:ivarNameString];
        }
    }

    free(ivars);
    return dict;
}

@end

第二次更新：

我已经描述的更新的解决方案(使用Florent’s PFObject / PFACL encoders替换className与parseClassName加上Martin Rybak’s PFFile encoder的组合)可以在下面的测试工具中工作(参见下面的代码),第二次调用saveInBackground调用在从NSKeyedUnarchiver还原后工作.

- (void)viewDidLoad {
    [super viewDidLoad];

    PFObject *testObject = [PFObject objectWithClassName:@"TestObject"];
    testObject[@"foo1"] = @"bar1";
    [testObject saveInBackground];

    BOOL success = [NSKeyedArchiver archiveRootObject:testObject toFile:[self returnFilePathForType:@"testObject"]];
    NSLog(@"Test object after archive (%@): %@",(success ? @"succeeded" : @"Failed"),testObject);

    testObject = [NSKeyedUnarchiver unarchiveObjectWithFile:[self returnFilePathForType:@"testObject"]];
    NSLog(@"Test object after restore: %@",testObject);

    // Change the object
    testObject[@"foo1"] = @"bar2";
    [testObject saveInBackground];
}

- (NSString *)returnFilePathForType:(NSString *)param {
    NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES) objectAtIndex:0];
    NSString *filePath = [docDir stringByAppendingPathComponent:[param stringByAppendingString:@".dat"]];

    return filePath;
}

但是,查看Parse服务器时,第二次调用saveInBackground创建了新版本的对象.

即使这超出了原始问题的范围,我将看看是否可以鼓励Parse服务器重新保存原始对象.同时请投票和/或接受答案,解决了在NSKeyedArchiving之后使用saveInBackground的问题.

最新更新：

这个问题原来只是一个时间问题 – 当NSKeyedArchiver发生时,第一个saveInBackground没有完成,因此在归档时objectId仍然为零,因此在第二个saveInBackground时仍然是一个新对象.使用一个块(类似于下面)来检测什么时候保存完成,可以调用NSKeyedArchiver也可以工作

以下版本不会导致保存第二个副本：

- (void)viewDidLoad {
    [super viewDidLoad];

    __block PFObject *testObject = [PFObject objectWithClassName:@"TestObject"];
    testObject[@"foo1"] = @"bar1";
    [testObject saveInBackgroundWithBlock:^(BOOL succeeded,NSError *error) {
        if (succeeded) {
            BOOL success = [NSKeyedArchiver archiveRootObject:testObject toFile:[self returnFilePathForType:@"testObject"]];
            NSLog(@"Test object after archive (%@): %@",testObject);

            testObject = [NSKeyedUnarchiver unarchiveObjectWithFile:[self returnFilePathForType:@"testObject"]];
            NSLog(@"Test object after restore: %@",testObject);

            // Change the object
            testObject[@"foo1"] = @"bar2";
            [testObject saveInBackground];
        }
    } ];

}