[数据存储之一]NSCoding协议练习

快来打我* 2022-08-18 12:05 136阅读 0赞

#import <Foundation/Foundation.h>
    
    @interface TestCodingProtocol : NSObject<NSCoding>
    #pragma mark- 持久化属性
    @property(nonatomic,copy,readwrite) NSString* myName;
    @property(nonatomic,assign,readwrite)NSInteger myIndex;
    #pragma mark- 实现协议方法
    - (void)encodeWithCoder:(NSCoder *)aCoder;
    - (id)initWithCoder:(NSCoder *)aDecoder;
    
    @end
    
    @interface TestCodingProtocolChild : TestCodingProtocol
    
    @property(nonatomic,assign,readwrite) NSInteger myIndexChild;
    -(void)encodeWithCoder:(NSCoder *)aCoder;
    -(id)initWithCoder:(NSCoder *)aDecoder;
    
    @end

#import "TestCodingProtocol.h"
    
    @implementation TestCodingProtocol
    
    -(void)encodeWithCoder:(NSCoder *)aCoder
    {
        if (aCoder) {
            [aCoder encodeObject:self.myName forKey:@"myName"];
            //self.myIndex为基础类型，不能用encodeObject
            [aCoder encodeInteger:self.myIndex forKey:@"myIndex"];
        }
    }
    
    -(id)initWithCoder:(NSCoder *)aDecoder
    {
        if (self = [super init]) {
            if (!aDecoder) {
                return self;
            }
            self.myName = [aDecoder decodeObjectForKey:@"myName"];
            self.myIndex = [aDecoder decodeIntegerForKey:@"myIndex"];
        }
        return self;
    }
    @end
    
    @implementation TestCodingProtocolChild
    
    -(void)encodeWithCoder:(NSCoder *)aCoder
    {
        [super encodeWithCoder:aCoder];
        [aCoder encodeInteger:self.myIndexChild forKey:@"myIndexChild"];
    }
    
    -(id)initWithCoder:(NSCoder *)aDecoder
    {
        if (self = [super initWithCoder:aDecoder]) {//这里如果用init的话，父类的内容得不到初始化。
            if (!aDecoder) {
                return self;
            }
            self.myIndexChild = [aDecoder decodeIntegerForKey:@"myIndexChild"];
        }
        return self;
    }
    @end

NSString* path = @"/Users/liyanq/Desktop";
        NSString* fPath = [path stringByAppendingPathComponent:@"copying.plist"];
        TestCodingProtocol* t = [[TestCodingProtocol alloc] init];
        t.myIndex = 5;
        t.myName = @"hello";
        
        TestCodingProtocolChild* tChild = [[TestCodingProtocolChild alloc] init];
        tChild.myIndex = 6;
        tChild.myName = @"child";
        tChild.myIndexChild = 7;
        //增加几个基础类型。
        NSString* s = @"helloworld";
        NSNumber* n = [NSNumber numberWithInteger:5];
        NSDate*   d = [NSDate date];
        NSArray*  r = [NSArray arrayWithObjects:tChild,t,s,n,d, nil];
        [NSKeyedArchiver archiveRootObject:r toFile:fPath];<span style="color: rgb(76, 191, 87); font-size: 11px; font-family: Menlo;">//</span><span style="color: rgb(76, 191, 87); font-family: 'Heiti SC Light'; font-size: 11px;">完成了存储。没有文件会创建，有的话会清除内容。</span>

NSArray* er = [NSKeyedUnarchiver unarchiveObjectWithFile:fPath];//完成了读取。
        [er enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
            if ([obj isKindOfClass:[TestCodingProtocolChild class]]) {
                TestCodingProtocolChild* buf = obj;//只能声明个变量了，不会强制转换。
                NSLog(@"myIndex is %ld, myName is %@, myIndexChild is %ld", buf.myIndex, buf.myName, buf.myIndexChild);
            }
            else if ([obj isKindOfClass:[TestCodingProtocol class]])
            {
                TestCodingProtocol* buf = obj;
                NSLog(@"myIndex is %ld, myName is %@", buf.myIndex, buf.myName);
            }
            else{
                NSLog(@"index is %ld,value is %@",idx,obj);
            }
        }];

总结下吧：

1，完成了对象的序列化与反序列化，而且对象可以继承自nsobject.

2，归档的形式来保存数据，只能一次性归档保存以及一次性解压。所以只能针对小量数据，而且对数据操作比较笨拙，即如果想改动数据的某一小部分，还是需要解压整个数据或者归档整个数据。

3，使用NSKeyedArchiver可以归档和恢复NSString、NSArray、NSDictionary、NSSet、NSDate、NSNumber和NSData等基本的Foundation对象

参考：http://blog.csdn.net/tianyitianyi1/article/details/7713103