将string字符串转换为array数组
NSArray *array = [Str componentsSeparatedByString:@","];
＝＝反向方法
将array数组转换为string字符串
NSString *tempString = [mutableArray componentsJoinedByString:@","];--分隔符
有字符串“A~B^C" ，我拆分为 "A", "B" 和 "C"?
NSString *str = @"A~B^C";
NSArray *arr = [str componentsSeparatedByCharactersInSet: [NSCharacterSet characterSetWithCharactersInString:@"^~"]];
NSLog(@"%@", arr);
／／字符
[NSCharacterSet whitespaceCharacterSet]