objective-c 编程基础（3.7 Foundation框架之字典）

oc中字典的定义：

1、存储无序键值对的集合

2、键不能相同

3、它只能保存对象，基本数据类型必须转换成NSNumber才能存储

字典的使用，如下图所示：

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
@autoreleasepool {
// 初始化
//1.创建1个空数组
NSDictionary *dictionary = [NSDictionary dictionary];
//2. 创建value和key
NSDictionary *dictionary2 = [NSDictionary dictionaryWithObjectsAndKeys:@"jack",@"name",@(18),@"age",@(YES),@"是否服役",@(18.5),@"money", nil];
NSLog(@"%@", dictionary2);
//3.字典的长度
NSLog(@"%i",dictionary2.count);
//4. 访问字典的元素
NSLog(@"姓名为%@",[dictionary2 objectForKey:@"name"]);
NSLog(@"年龄为%i",[[dictionary2 objectForKey:@"age"] intValue]);
NSLog(@"是否服役%@",[dictionary2 objectForKey:@"是否服役" ]);
NSLog(@"存款为%@",[dictionary2 objectForKey:@"money"]);
//5.遍历
for (NSObject *object in [dictionary2 keyEnumerator]) {
NSLog(@"字典的key为%@,value为%@",object,[dictionary2 objectForKey:object]);
}
//6.使用可变字典
NSMutableDictionary *dictionary3 =[NSMutableDictionary dictionaryWithObjectsAndKeys:@"jack",@"name",@(18),@"age",@(YES),@"是否服役",@(18.5),@"money", nil];
NSLog(@"dictionary3为%@",dictionary3);
//7.可变字典，添加新元素
[dictionary3 setObject:@"去上课" forKey:@"状态"];
NSLog(@"dictionary3为%@",dictionary3);
//8.可变字典，删除元素
[dictionary3 removeObjectForKey:@"age"];
NSLog(@"dictionary3为%@",dictionary3);
}
return 0;
}