[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.NSArray 转换成 NSMutableArray
         NSArray *array = @[@"one", @"two", @"three"];
         NSMutableArray *muArray = [NSMutableArrayarrayWithArray:array];
         NSLog(@"muArray = %@", muArray);

         // 2.NSDictionary 转换成 NSMutableDictionary
         NSDictionary *dic = @{@"one":@"", @"two":@"", @"three":@""};
         NSMutableDictionary *muDic = [NSMutableDictionarydictionaryWithDictionary:dic];
         NSLog(@"muDic = %@", muDic);

         // 3.NSArray -> NSSet -> NSMutableSet
         NSSet *set = [NSSetsetWithArray:array];
         NSMutableSet *muSet = [NSMutableSetsetWithSet:set];
         NSLog(@"muSet = %@", muSet);

         // 4.NSDcitionary -> NSArray
         NSArray *allKeys = [dic allKeys];
         NSLog(@"allKeys = %@", allKeys);
         NSArray *allValues = [dic allValues];
         NSLog(@"allValues = %@", allValues);

         // 5.NSString -> NSArray
         NSString *str = @"www.baidu.com";
         NSArray *array2 = [str componentsSeparatedByString:@"."];
         NSLog(@"array2 = %@", array2);