ios - 如何将 NSString 格式化为美国的电话号码？

Question

我有一个简单的应用程序可以帮助招聘人员在事件中收集信息。一个表单字段用于电话号码，我想要一种简单的方法来在用户键入时重新格式化电话号码。

电话号码应随着用户键入而变化，因此一串数字的示例输出应如下所示:

1
1 (20)
1 (206) 55
1 (206) 555-55
1 (206) 555-5555

或者，如果用户没有在区号前输入 1，则电话号码会像这样演变:

(20)
(206) 55
(206) 555-55
(206) 555-5555

如果电话号码太长，那么它应该只显示一串数字:

20655555555555555

Answer 1

这是我所做的:UITextFieldDelegate 通过获取 UITextField 的文本处理 textField:shouldChangeCharactersInRange :replacementString: 方法，并运行我写的一个小方法:

-(void)updatePhoneNumberWithString:(NSString *)string {

    NSMutableString *finalString = [NSMutableString new];
    NSMutableString *workingPhoneString = [NSMutableString stringWithString:string];

    if (workingPhoneString.length > 0) {
    //This if statement prevents errors when the user deletes the last character in the textfield.

        if ([[workingPhoneString substringToIndex:1] isEqualToString:@"1"]) {
        //If the user typed a "1" as the first digit, then it's a prefix before the area code.
            [finalString appendString:@"1 "];
            [workingPhoneString replaceCharactersInRange:NSMakeRange(0, 1) withString:@""];
        }

        if (workingPhoneString.length < 3) {
        //If the user is dialing the area code...
            [finalString appendFormat:[NSString stringWithFormat:@"(%@)", workingPhoneString]];

        } else if (workingPhoneString.length < 6) {
        //If the user is dialing the 3 digits after the area code...
            [finalString appendFormat:[NSString stringWithFormat:@"(%@) %@", 
                                       [workingPhoneString substringWithRange:NSMakeRange(0, 3)], 
                                       [workingPhoneString substringFromIndex:3]]];

        } else if (workingPhoneString.length < 11) {
        //If the user is dialing the last 4 digits of the phone number...
            [finalString appendFormat:[NSString stringWithFormat:@"(%@) %@-%@", 
                                       [workingPhoneString substringWithRange:NSMakeRange(0, 3)], 
                                       [workingPhoneString substringWithRange:NSMakeRange(3, 3)],
                                       [workingPhoneString substringFromIndex:6]]];
        } else {
        //If the user's typed in a bunch of characters, then just show the full string.
            finalString = phoneString;
        }

        phoneNumberField.text = finalString;
    } else {
    //If the user changed the textfield to contain no text at all...
        phoneNumberField.text = @"";
    }

}

希望对你有帮助!