iOS TextField只能输入字母和数字

项目上有个输入税号的需求，要求只能输入字母和数字，并且字母只能是大写字母

1.首先设置键盘样式

self.textField.keyboardType = UIKeyboardTypeASCIICapable;

2.设置宏

#define NUM @"0123456789"
#define ALPHA @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
#define ALPHANUM @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"

3.textFieldDelegate方法

// 只能输入字母和数字
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:ALPHANUM] invertedSet];
    NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
    return [string isEqualToString:filtered];
}
// 小写字母转大写字母
- (void)textFieldDidEndEditing:(UITextField *)textField {
    textField.text = [textField.text uppercaseString];
}