xcode - 如何检查 NSString 的第一个值

Question

我有一个像这样的字符串 NSString *mobile=@"09894598945"。如何检查上面字符串的第一个字符为零？

Answer 1

As suggested in comment hasPrefix is best fit here. But you can also use substringWithRange function as well. It is enough flexible to check nth character of the string as well:

if([[mobile substringWithRange:NSMakeRange(0, 1)] isEqualToString:@"5"])
{
   // started with 5
}

EDIT

As discussed in comment with Nikolai Ruhe, function substringWithRange will not work for surrogate pairs as mentioned in comments. This is the limitation of this function.

Use hasPrefix instead.

Answer 2

NSString *mobile=@"09894598945";

    if ([mobile characterAtIndex:0] == '0')
    {
        NSLog(@"Yes it contain 0");
    }

或者

if ([mobile hasPrefix:@"0"])
    {
        NSLog(@"Yes it contain 0");
    }