符合nscoding的对象将不会写入文件 [英] objects conforming to nscoding will not writetofile
问题描述
我想将一个Question对象数组写入文件,但是以某种方式writeToFile没有做任何事情.一个问题有一个所有者和一个答案对象数组.答案也有一个所有者.他们三个都符合NSCoding协议(据我所知).
I want to write an array of Question objects to file, but somehow writeToFile isn't doing anything. A Question has an Owner and and an array of Answer objects. An Answer has an Owner as well. All three of them conform to the NSCoding protocol (as far as I know).
从下面的代码中,结果返回NO.不知道我在做什么错,因为我正在为所有内容实施NSCoding,对吗?
From the code below, result returns NO. No clue what I'm doing wrong, since I am implementing NSCoding for everything, right?
Question.h
#import <Foundation/Foundation.h>
#import "Owner.h"
@interface Question : NSObject <NSCoding> {
NSString *questionId;
NSString *questionRevision;
NSString *text;
NSDate *date;
NSMutableArray *answers;
NSString *page;
NSNumber *questionLocation;
Owner *owner;
}
@property (nonatomic, retain) NSString *questionId;
@property (nonatomic, retain) NSString *questionRevision;
@property (nonatomic, retain) NSString *text;
@property (nonatomic, retain) NSDate *date;
@property (nonatomic, retain) NSMutableArray *answers;
@property (nonatomic, retain) NSString *page;
@property (nonatomic, retain) NSNumber *questionLocation;
@property (nonatomic, retain) Owner *owner;
@end
Question.m
#import "Question.h"
#import "Answer.h"
@implementation Question
@synthesize questionId, questionRevision, text, date, answers, page, questionLocation, owner;
- (void)encodeWithCoder:(NSCoder *)coder
{
//[super encodeWithCoder:coder];
[coder encodeObject:questionId forKey:@"questionId"];
[coder encodeObject:questionRevision forKey:@"questionRevision"];
[coder encodeObject:text forKey:@"text"];
[coder encodeObject:date forKey:@"date"];
[coder encodeObject:answers forKey:@"answers"];
[coder encodeObject:page forKey:@"page"];
[coder encodeObject:questionLocation forKey:@"questionLocation"];
[coder encodeObject:owner forKey:@"owner"];
}
- (id)initWithCoder:(NSCoder *)decoder
{
//self = [super initWithCoder:decoder];
self = [super init];
self.questionId = [decoder decodeObjectForKey:@"questionId"];
self.questionRevision = [decoder decodeObjectForKey:@"questionRevision"];
self.text = [decoder decodeObjectForKey:@"text"];
self.date = [decoder decodeObjectForKey:@"date"];
self.answers = [decoder decodeObjectForKey:@"answers"];
self.page = [decoder decodeObjectForKey:@"page"];
self.questionLocation = [decoder decodeObjectForKey:@"questionLocation"];
self.owner = [decoder decodeObjectForKey:@"owner"];
}
@end
Answer.h
#import <Foundation/Foundation.h>
#import "Owner.h"
@interface Answer : NSObject <NSCoding> {
Owner *owner;
NSString *text;
NSDate *date;
}
@property (nonatomic, retain) Owner *owner;
@property (nonatomic, retain) NSString *text;
@property (nonatomic, retain) NSDate *date;
@end
答案
#import "Answer.h"
@implementation Answer
@synthesize owner, text, date;
- (void)encodeWithCoder:(NSCoder *)coder
{
//[super encodeWithCoder:coder];
[coder encodeObject:owner forKey:@"owner"];
[coder encodeObject:text forKey:@"text"];
[coder encodeObject:date forKey:@"date"];
}
- (id)initWithCoder:(NSCoder *)decoder
{
//self = [super initWithCoder:decoder];
self = [super init];
self.owner = [decoder decodeObjectForKey:@"owner"];
self.text = [decoder decodeObjectForKey:@"text"];
self.date = [decoder decodeObjectForKey:@"date"];
}
@end
Owner.h
#import <Foundation/Foundation.h>
@interface Owner : NSObject <NSCoding> {
NSString *name;
NSString *photoFileName;
}
@property (nonatomic, retain) NSString *name;
@property (nonatomic, retain) NSString *photoFileName;
@end
Owner.m
#import "Owner.h"
@implementation Owner
@synthesize name, photoFileName;
- (void)encodeWithCoder:(NSCoder *)coder
{
//[super encodeWithCoder:coder];
[coder encodeObject:name forKey:@"name"];
[coder encodeObject:photoFileName forKey:@"photoFileName"];
}
- (id)initWithCoder:(NSCoder *)decoder
{
//self = [super initWithCoder:decoder];
self = [super init];
self.name = [decoder decodeObjectForKey:@"name"];
self.photoFileName = [decoder decodeObjectForKey:@"photoFileName"];
}
@end
相关代码行
BOOL result = [questions writeToFile:@"Users/brunoscheele/Desktop/questions.plist" atomically:YES];
推荐答案
writeToFile:atomically:
写入属性列表文件,而不是序列化存档.无法通过实现NSCoding
来扩展属性列表类型,并且由于您的对象不是属性列表支持的类型之一,因此无法将它们写入属性列表.
writeToFile:atomically:
writes property list files, not serialised archives. Property list types can't be extended by implementing NSCoding
, and as your objects aren't one of the types supported by property lists, then they can't be written to a property list.
要存档对象,您需要使用NSAchiver
,例如:
To archive your objects, you'll need to use an NSAchiver
, for example:
[NSKeyedArchiver archiveRootObject:questions
toFile:@"some/path/questions.archive"]
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