輸入框禁止首位輸入小數點而且保留小數

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    
    if ([textField.text rangeOfString:@"."].location != NSNotFound) {
        if ([string isEqualToString:@"."]) {
            return NO;
        }else{
            NSRange lRange = [textField.text rangeOfString:@"."];
            if (range.location - lRange.location < 5) {
                return YES;
            }else{
                return NO;
            }
            
        }
    }else {
        if([textField.text length] == 0) {
            
            if([string characterAtIndex:0] == '.') {
                
                [textField.text stringByReplacingCharactersInRange:range withString:@""];
                
                return NO;
                
            }
            
        }else {
            return YES;
        }
    }
    
    return YES;
}