==========android培训、ios培训、java培训、期待与您交流==========
一、NSSet:
NSSet
NSSet里面存储的元素没有顺序,NSArray中的元素有顺序。
NSSet *s = [NSSet set]; // 创建一个空的Set,永远是空,不可变。
NSSet *s2 = [NSSet setWithObjects:@"jack",@"rose",nil];
NSString *str = [s2 anyObject]; // 随机取出一个元素
NSMutableSet
NSMutableSet s = [NSMutableSet setWithObject:@"jack"];
[s addObject:@"rose"];
[s removeObject:(id)];
二、NSDictionary和NSMutableDictionary
<1>NSDictionary
创建一个NSDictionary 不可变
NSDictionary 是没有顺序的
key ------> value
键值对
// 创建方法
NSDictionary *dict = [NSDictionary dictionaryWithObject:(id)
forKey:(id<NSCopying>)];
NSDictionary *dict = [NSDictionary
dictionaryWithObject:@"jack" forKey:@"name"]
[dict objectForKey:(id)];
NSLog(@"%@",obj);
创建方法二
NSArry *keys =
@[@"name",@"adress"];
NSArry *values = @[@"jack",@"北京"];
NSDictionary *dict = [NSDictionary dictionaryWithObjects:values
forKeys:keys];
创建方法三:
NSDictionary *dict = [NSDictionary
dictionaryWithObjectsAndKeys:
@"jack",@"name",
@"北京",@"adress",
@"351868695",@"qq",
nil];
id
obj = dict objectForKey:@"qq"];
创建方法四:
编译器特性:
//
注意返回NSDictionary类型 创建可变字典不能用这中方法
NSDictionary *dict = @{@"name" :
@"jack",@"adress" : @"北京"};
id obj =
dict[@"name"];
NSLog(@"%@",obj);
dict.count;//
返回键值对的个数
<2>NSMutableDictionary
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
[dict setObject:@"jack" forKey:@"name"];
[dict setObject:@"北京"
forKey:@"adress"];
[dict setObject:@"rose" forKey:@"name"]; // 把jack覆盖,
dict.count ;// 还是2 因为
rose覆盖了jack
[dict removeObjectForKey:(id)];
打印字典:
NSLog(@"%@",dict);结果是
{
adress = \U5317\U4eac;
name = rose;
}
字典的遍历
方法一:
NSDictionary *dict =
@{@"qq" : "123",@"name" : @"jack"};
NSArray *keys = [dict allKeys]; //
该方法把字典中所有的key返回来,存到一个数组中,注意这里是无序的
for(int i = 0; i<dict.count;
i++)
{
NSString *key = keys[i];
NSString *object = dict[key]; //
根据key的值取出value
NSLog(@"%@ = %@",key,object);
}
方法二:
[dict enumerateKeysAndObjectsUsingBlock:
^(id key, id obj,BOOL
*stop){
NZLog(@"%@ - %@",key, obj);
}];
==========android培训、ios培训、java培训、期待与您交流==========
黑马程序员——Foundation学习笔记(NSSet和NSMutableSet),布布扣,bubuko.com