将NSMutableArray保存到NSUserDefaults的最佳方法是什么？

Question

我有一个名为Occasion的自定义对象,定义如下:

#import <Foundation/Foundation.h>


@interface Occasion : NSObject {

NSString *_title;
NSDate *_date;
NSString *_imagePath;    

}

@property (nonatomic, retain) NSString *title;
@property (nonatomic, retain) NSDate *date;
@property (nonatomic, retain) NSString *imagePath;

现在我有一个NSMutableArray of Occasions,我想保存到NSUserDefaults.我知道这是不可能的,所以我想知道哪种方法最简单？如果序列化是答案,那么如何？因为我阅读了文档但却无法理解它的完整工作方式.

Answer 1

您应该使用类似NSKeyedArchiver的序列化数组NSData,将其保存到NSUserDefaults以后再用于NSKeyedUnarchiver反序列化:

NSData *serialized = [NSKeyedArchiver archivedDataWithRootObject:myArray];
[[NSUserDefaults standardUserDefaults] setObject:serialized forKey:@"myKey"];

//...

NSData *serialized = [[NSUserDefaults standardUserDefaults] objectForKey:@"myKey"];
NSArray *myArray = [NSKeyedUnarchiver unarchiveObjectWithData:serialized];

您需要NSCoding在Occasion类中实现协议并正确保存各种属性才能使其正常工作.有关更多信息,请参阅" 存档和序列化编程指南".执行此操作不应超过几行代码.就像是:

- (void)encodeWithCoder:(NSCoder *)coder {
    [super encodeWithCoder:coder];

    [coder encodeObject:_title forKey:@"_title"];
    [coder encodeObject:_date forKey:@"_date"];
    [coder encodeObject:_imagePath forKey:@"_imagePath"];
}

- (id)initWithCoder:(NSCoder *)coder {
    self = [super initWithCoder:coder];

    _title = [[coder decodeObjectForKey:@"_title"] retain];
    _date = [[coder decodeObjectForKey:@"_date"] retain];
    _imagePath = [[coder decodeObjectForKey:@"_imagePath"] retain];

    return self;
}