确定字符串的第一个字符是否为1

Question

Basically I'm working on something that looks like the phone apps keypad. Everything else is inputting as it should but what I'm trying to figure out is how on this last one to get it when a 1 is inputted first that the number would look like 1 (555) 555-5555. I'm sure my code will need some tweaking to the substringfromindexes to get it to match up, but what I'm trying to get to happen now is just to check if the entered strings first number is a one or not. Because if it is not it will just bypass this part of code.

else if ([self.self.enteredPhoneNumberString length] == 11 && [self.enteredPhoneNumberString characterAtIndex:0] == '1') {
        NSString *firstNum = [self.enteredPhoneNumberString substringToIndex:1];
        NSString *createFirst = [self.enteredPhoneNumberString substringFromIndex:3];
        NSString *firstThree = [createFirst substringToIndex:3];
        NSString *createSecond = [self.enteredPhoneNumberString substringFromIndex:3];
        NSString *secondThree = [createSecond substringToIndex:3];
        NSString *lastSet = [self.enteredPhoneNumberString substringFromIndex:6];
        self.label.text = [NSString stringWithFormat:@"%@ (%@) %@-%@", firstNum, firstThree, secondThree, lastSet];
    }

If you know of the way to adjust the substrinFromIndex to get the effect I'm going for too by all means that would save me time tampering until I find the right order. Thanks in advance for all help. :)

Oh and btw with the above code it did a breakpoint when I got to the this part in the code.

FIX:

Thanks for all the help it works now. Ended up doing this and for some reason the breakpoint doesnt happen when it is done here.

else if ([self.self.enteredPhoneNumberString length] >= 11 ) {
    if ([self.enteredPhoneNumberString characterAtIndex:0] == '1' && [self.self.enteredPhoneNumberString length] == 11) {
        NSString *firstNum = [self.enteredPhoneNumberString substringToIndex:1];
        NSString *createFirst = [self.enteredPhoneNumberString substringFromIndex:1];
        NSString *firstThree = [createFirst substringToIndex:3];
        NSString *createSecond = [self.enteredPhoneNumberString substringFromIndex:4];
        NSString *secondThree = [createSecond substringToIndex:3];
        NSString *lastSet = [self.enteredPhoneNumberString substringFromIndex:7];
        self.label.text = [NSString stringWithFormat:@"%@ (%@) %@-%@", firstNum, firstThree, secondThree, lastSet];
    }
    else{
       self.label.text = [NSString stringWithFormat:@"%@", enteredPhoneNumberString]; 
    }
}

And ya it does seem pointless to have to check if the length is 11 again, but because it was causing issues the previous way I didnt really have much of a choice because I needed it to know whether it exceeded 11 or not so it could start doing that else.

Answer 1

It could be the if statement above where your code starts is true...

else if ([self.self.enteredPhoneNumberString length] == 11 && [self.enteredPhoneNumberString characterAtIndex:0] == '1') {

needs some cleaning up. You shouldn't check for length 11 here, just check for length > 0 and whether first character is a 1. Do the necessary formatting, trim white space and (), then check the length. Also, self.self is a potential problem, drop the second self

Please disregard CocoaFu's comment his solution is better, but the comment is misleading.

In the following code, my log statement shows up in the console

NSString * test = [NSString stringWithString:@"test"];
unichar c = [adjusted characterAtIndex:0];

if (c == 't')   {
    NSLog(@"can compare char");
}

Answer 2

if [[self.enteredPhoneNumberString substringToIndex:1] isEqualToString:@"1"] {

}

I think this is what you are asking for...

Answer 3

第一个字符最简单的比较：

[self.enteredPhoneNumberString hasPrefix:@"1"]