Objective C : How to get the Ascii Integer value of the first letter of a NSString?

问题

Objective C : How to get the Ascii Integer value of the first letter of a NSString?

回答1:

if ([aString length] > 0) {
    unichar firstCharacter = [aString characterAtIndex: 0];
    // ...
}

That's all. unichar is an alias of unsigned short and so is an integer type. However, there is no guarantee the character is part of ASCII, as NSString is Unicode-based.

回答2:

unichar ch = [myString characterAtIndex:0]

Now as the name specified, it returns the unicode character value unichar which is actually a typedef of unsigned short. NSString is not ASCII string, but if the first character is really an ASCII character then you will get the correct ASCII value. And if the string is empty then this will raise an exception.

回答3:

If you really need to do it, turn the first character of the string into an NSData with ASCII encoding and then read it back.

There's some help in the String Programming Guide.

来源：https://stackoverflow.com/questions/4422385/objective-c-how-to-get-the-ascii-integer-value-of-the-first-letter-of-a-nsstri