NSCoding

February 24th, 2016

目录

NSCoding说明

NScoding 是一个协议，主要有下面两个方法 -(id)initWithCoder:(NSCoder *)coder;//从coder中读取数据，保存到相应的变量中，即反序列化数据 -(void)encodeWithCoder:(NSCoder *)coder;// 读取实例变量，并把这些数据写到coder中去。序列化数据 NSCoder 是一个抽象类，抽象类不能被实例话，只能提供一些想让子类继承的方法。 NSKeyedUnarchiver 从二进制流读取对象。 NSKeyedArchiver 把对象写到二进制流中去。

例子

@interface Book : NSObject <NSCoding>
@property NSString *title;
@property NSString *author;
@property NSUInteger pageCount;
@property NSSet *categories;
@property (getter = isAvailable) BOOL available;
@end

@implementation Book

#pragma mark - NSCoding

- (id)initWithCoder:(NSCoder *)decoder {
    self = [super init];
    if (!self) {
        return nil;
    }

    self.title = [decoder decodeObjectForKey:@"title"];
    self.author = [decoder decodeObjectForKey:@"author"];
    self.pageCount = [decoder decodeIntegerForKey:@"pageCount"];
    self.categories = [decoder decodeObjectForKey:@"categories"];
    self.available = [decoder decodeBoolForKey:@"available"];

    return self;
}

- (void)encodeWithCoder:(NSCoder *)encoder {
    [encoder encodeObject:self.title forKey:@"title"];
    [encoder encodeObject:self.author forKey:@"author"];
    [encoder encodeInteger:self.pageCount forKey:@"pageCount"];
    [encoder encodeObject:self.categories forKey:@"categories"];
    [encoder encodeBool:[self isAvailable] forKey:@"available"];
}

@end

序列化写入磁盘

Archiving
[NSKeyedArchiver archiveRootObject:books toFile:@"/path/to/archive"];


Unarchiving
[NSKeyedUnarchiver unarchiveObjectWithFile:@"/path/to/archive"];

序列化写入NSUserDefaults

Archiving
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:books];
[[NSUserDefaults standardUserDefaults] setObject:data forKey:@"books"];
Unarchiving
NSData *data = [[NSUserDefaults standardUserDefaults] objectForKey:@"books"];
NSArray *books = [NSKeyedUnarchiver unarchiveObjectWithData:data];


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