第四章 Runtime应用：实现字典和模型的自动转换

拼搏现实的明天。 2022-05-21 12:23 207阅读 0赞

用runtime提供的函数遍历Model自身所有属性，如果属性在json中有对应的值，则将其赋值。

示例

#import <Foundation/Foundation.h>
    
    @interface Person : NSObject
    
    - (instancetype)initWithDict:(NSDictionary *)dict;
    
    @property (nonatomic, strong) NSString *name;
    @property (nonatomic, strong) NSNumber *age;
    @property (nonatomic, strong) NSString *address;
    @property (nonatomic, strong) NSString *company;
    @property (nonatomic, strong) NSString *job;
    
    @end

#import "Person.h"
    #import <objc/runtime.h>
    
    @implementation Person
    
    #pragma mark - 模型转换
    
    - (instancetype)initWithDict:(NSDictionary *)dict
    {
        self = [super init];
        if (self)
        {
            // 获取类的属性及属性对应的类型
            NSMutableArray *keys = [NSMutableArray array];
            NSMutableArray *attributes = [NSMutableArray array];
    
            unsigned int outCount;
            objc_property_t *properties = class_copyPropertyList([self class], &outCount);
            for (int i = 0; i < outCount; i ++)
            {
                objc_property_t property = properties[i];
                // 通过property_getName函数获得属性的名字
                NSString *propertyName = [NSString stringWithCString:property_getName(property) encoding:NSUTF8StringEncoding];
                [keys addObject:propertyName];
                // 通过property_getAttributes函数可以获得属性的名字和@encode编码
                NSString *propertyAttribute = [NSString stringWithCString:property_getAttributes(property) encoding:NSUTF8StringEncoding];
                [attributes addObject:propertyAttribute];
            }
            // 立即释放properties指向的内存
            free(properties);
    
            // 根据类型给属性赋值
            for (NSString *key in keys)
            {
                id value = [dict valueForKey:key];
                if (value == nil)
                {
                    continue;
                }
                [self setValue:value forKey:key];
            }
        }
        return self;
    }
    
    @end

使用

// 模型转换
    NSDictionary *dict = @{@"school":@"Jiaying",@"name":@"devZhang",@"age":@(35),@"company":@"ShengXue",@"job":@"iOSDev",@"address":@"龙岗坂田国际中心"};
    Person *person = [[Person alloc] initWithDict:dict];
    NSLog(@"name: %@", person.name);
    
    // 打印结果
    2018-07-07 00:43:42.084651+0800 DemoRuntime[2032:91805] name: devZhang