[OC Foundation框架 - 21] NSSet集合 & 集合之间的转换

A.NSSet

跟NSArray一样，不可变

NSArray 自然顺序

NSSet是无序的

NSSet不允许存入重复元素，可以用来过滤重复元素

 

也有可变的NSMutableSet

 

B.集合转换

       

 1  // 1.NSArray 转换成 NSMutableArray

 2         NSArray *array = @[@"one", @"two", @"three"];

 3         NSMutableArray *muArray = [NSMutableArrayarrayWithArray:array];

 4         NSLog(@"muArray = %@", muArray);

 5        

 6        

 7         // 2.NSDictionary 转换成 NSMutableDictionary

 8         NSDictionary *dic = @{@"one":@"1", @"two":@"2", @"three":@"3"};

 9         NSMutableDictionary *muDic = [NSMutableDictionarydictionaryWithDictionary:dic];

10         NSLog(@"muDic = %@", muDic);

11        

12         // 3.NSArray -> NSSet -> NSMutableSet

13         NSSet *set = [NSSetsetWithArray:array];

14         NSMutableSet *muSet = [NSMutableSetsetWithSet:set];

15         NSLog(@"muSet = %@", muSet);

16        

17         // 4.NSDcitionary -> NSArray

18         NSArray *allKeys = [dic allKeys];

19         NSLog(@"allKeys = %@", allKeys);

20         NSArray *allValues = [dic allValues];

21         NSLog(@"allValues = %@", allValues);

22        

23         // 5.NSString -> NSArray

24         NSString *str = @"www.baidu.com";

25         NSArray *array2 = [str componentsSeparatedByString:@"."];

26         NSLog(@"array2 = %@", array2);