将NSString字符串转换为NSArray数组，componentsSeparatedByString，将array数组转换为string字符串，componentsJoinedByString

将string字符串转换为array数组

NSString *a = [[NSString alloc] initWithString : @"冬瓜，西瓜，火龙果，大头，小狗" ];

    NSArray *b = [a componentsSeparatedByString:@"，"];

    NSString *a3 = [b objectAtIndex:2];

    NSLog(@"   b的第三个东东是： %@", a3);

    [a release];

 NSArray  *array = [Str componentsSeparatedByString:@","];

＝＝反向方法

将array数组转换为string字符串

NSArray *array = ［NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
    NSString *string = [array componentsJoinedByString:@","];
    NSLog(@"string:%@",string);

 NSString *tempString = [mutableArray componentsJoinedByString:@","];--分隔符