iOS-Runtime实现对象的归档/解档

工作中，Runtime实现对象的归档/解档的功能经常用到。之前没有做整理，今天特意整理了一下，也算作为一个知识点吧。方便自己的学习巩固。

其实，这个功能实现起来很简单。就下面几步：
第一步：创建类，遵守NSCoding协议
第二步：实现NSCoding协议中的两个方法

- (void)encodeWithCoder:(NSCoder *)aCoder；
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder；

第三步：利用NSKeyedArchiver归档/NSKeyedUnarchiver解档

接下来，我就新建一个类CustomClass，随便添加几个属性，来利用以上步骤实现该功能。

#import <Foundation/Foundation.h>

@interface CustomClass : NSObject<NSCoding>

//随便添加了几个属性
@property(nonatomic,copy)NSString *attribute1;

@property(nonatomic,copy)NSString *attribute2;

@property(nonatomic,assign)NSInteger attribute3;

@property(nonatomic,assign)BOOL attribute4;

@end

CustomClass.m中的实现代码：

#import "CustomClass.h"
#import <objc/runtime.h>
@implementation CustomClass
//归档
- (void)encodeWithCoder:(NSCoder *)aCoder{
    unsigned int count = 0;
    //取到所有的Ivar
    Ivar *ivars = class_copyIvarList([self class], &count);
    //遍历 逐个属性归档
    for (int i = 0; i < count; i++) {
        //找到Ivar
        Ivar ivar = ivars[i];
        //找到Ivar对应的名称
        const char *name = ivar_getName(ivar);
        //找到key
        NSString *key = [NSString stringWithUTF8String:name];
        //key对应的value值
        id value = [self valueForKey:key];
        //键值保存
        [aCoder encodeObject:value forKey:key];
    }
    free(ivars);
}

//解档
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder{
    
    self = [super init];
    if (self) {
        unsigned int count = 0;
        Ivar *ivars = class_copyIvarList([self class], &count);
        for (int i = 0; i < count; i++) {
            //拿到每一个Ivar 在这里拿到的是数组的首地址
            Ivar ivar = ivars[i];
            //ivar对应的名称
            const char *name = ivar_getName(ivar);
            //属性key
            NSString *key = [NSString stringWithUTF8String:name];
            //属性value
            id value = [aDecoder decodeObjectForKey:key];
            //KVC 将值设置到对应的属性上面
            [self setValue:value forKey:key];
        }
        free(ivars);
    }
    return self;
}
@end

接下来就是具体的应用：
存

    CustomClass *model = [[CustomClass alloc]init];
    
    model.attribute1 = @"刘高见";
    model.attribute2 = @"我是谁";
    model.attribute3 = 20;
    model.attribute4 = YES;
    //路径
    NSString *path = NSTemporaryDirectory();
    NSString *filePath = [path stringByAppendingString:@"liugaojian.file"];
    //归档
    [NSKeyedArchiver archiveRootObject:model toFile:filePath];

//取

    //路径
    NSString *path = NSTemporaryDirectory();
    NSString *filePath = [path stringByAppendingString:@"liugaojian.file"];
    
    //归档
   CustomClass *model = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];

    NSLog(@"attribute1=%@-------attribute2=%@-------attribute3=%ld--------attribute4=%d",model.attribute1,model.attribute2,(long)model.attribute3,model.attribute4);

哈哈 over～～～