pragma mark 不可变字典NSDictionary

pragma mark 概念

/**
 NSDictionary
 1.创建
字典_单个键值对 (dictionaryWithObject:forKey)
字典_多个个键值对 (dictionaryWithObjects:forKeys)

 2.取值
 字典_单个值 获取  (objectForKey)  字典_单个值 快速获取 dict[@"value"];
 字典_多个键值对 @{@"v1":@"k1",@"v2",@"k2"}
 
 3. 获取字典的键值对 个数
 (dict.count)
 
 4.遍历字典
 4.1for
 
 for (int i = 0; i<dict.count; ++i) {
 // 获取 字典中所有的key
 NSArray *keys = [dict allKeys];
 // 取出当前位置 对应的key
 NSLog(@"%@",keys[i]);
 
 NSString *key = keys[i];
 NSString *value = dict[key];
 NSLog(@"key = %@, value = %@",key, value);
 
 }
 
 4.2 for in 
 // 如何通过 for in遍历字典 , 会将所有的key赋值 给前面的obj
 for (NSDictionary *key in dict) {
 NSString *value = dict[key];
 NSLog(@"key2 = %@, value2 = %@",key, value);
 }
 
 4.3 (enumerateKeysAndObjectsUsingBlock)
 [dict enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
 NSLog(@"key3 = %@, value3 = %@",key, obj);
 
 }];
 */

pragma mark 代码

#import <Foundation/Foundation.h>
#pragma mark 类

#pragma mark main函数
int main(int argc, const char * argv[])
{
 
#pragma mark 不可变字典NSDictionary
    
#warning 1.如何创建 (dictionaryWithObject:forKey)
    // obj 值 \
        key 键
    NSDictionary *dict = [NSDictionary dictionaryWithObject:@"lyh" forKey:@"name"];
#warning 1.1.取值 (objectForKey)
    NSString *name = [dict objectForKey:@"name"];
    NSLog(@"%@",name);
    
#warning 2. 创建多个键值对
    // 注意: key 和 value 是一一对应的
    NSDictionary *dict1 = [NSDictionary dictionaryWithObjects:@[@"lyh",@"24",@"172"] forKeys:@[@"name",@"age",@"height"]];
    NSLog(@"%@ %@ %@",[dict1 objectForKey:@"name"],[dict1 objectForKey:@"age"],[dict1 objectForKey:@"height"]);

#warning 3.简单创建 字典 @{键:值}
//    NSDictionary *dict2 = @{key:value};
    NSDictionary *dict2 = @{@"name":@"lyh"};
    NSLog(@"%@",[dict2 objectForKey:@"name"]);
    NSLog(@"%@",dict2[@"name"]);
    
 
#warning 4.创建多个 键值对 字典
    NSDictionary *dict3 = @{@"name":@"lyh",@"age":@"25",@"height":@"170"};
    NSLog(@"%@ %@ %@",dict3[@"name"],dict3[@"age"],dict3[@"height"]);
    
    
#pragma mark 5.字典的遍历
#warning 5.1 获取键值对
    dict = @{@"name":@"lys",@"age":@"28",@"height":@"171"};
    // 如何获取字典中 key 和 value的个数, 在字典中 key称之为 键, value称之为 值
    NSLog(@"count = %lu",dict.count);
 
    
#warning 5.2 字典遍历
    // for
#warning 5.2.1 字典遍历 (for)
    for (int i = 0; i<dict.count; ++i) {
        // 获取 字典中所有的key
        NSArray *keys = [dict allKeys];
        // 取出当前位置 对应的key
        NSLog(@"%@",keys[i]);
        
        NSString *key = keys[i];
        NSString *value = dict[key];
        NSLog(@"key = %@, value = %@",key, value);
        
    }
#warning 5.2.2 字典遍历 (for in)
    // 如何通过 for in遍历字典 , 会将所有的key赋值 给前面的obj
    for (NSDictionary *key in dict) {
        NSString *value = dict[key];
    }
    
    
#warning 5.2.3 字典遍历 (enumerateKeysAndObjectsUsingBlock)

    [dict enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
        NSLog(@"key3 = %@, value3 = %@",key, obj);

    }];
    
    
#warning 6. 字典文件读写
    dict = @{@"name":@"lyh",@"age":@"34"};
    
    [dict enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, id  _Nonnull obj, BOOL * _Nonnull stop) {
        NSLog(@"key4 = %@, value = %@",key, obj);
        
    }];
    
    // XML 扩展名plist
    int flag = [dict writeToFile:@"/Users/liyuhong165/Desktop/info.plist" atomically:YES];
    NSLog(@"flag  = %d",flag);
    
    // 注意: 字典和数组 不同, 字典中保存的数 都是无序的
    NSDictionary *newDict = [NSDictionary dictionaryWithContentsOfFile:@"/Users/liyuhong165/Desktop/info.plist"];
    NSLog(@"%@",newDict);
    
    
#warning 7.数组是有序的 字典是无序的
    NSArray *arr = @[@10,@30,@50,@121];
    [arr writeToFile:@"/Users/liyuhong165/Desktop/info.plist" atomically:YES];
    return 0;
}