UITextField 只能输入字母\数字的方法之一

UITextField 只能输入字母\数字的方法之一 

#define ALPHA @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz "

#define NUMBERS @"0123456789"

#define ALPHANUM @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 "

#define NUMBERSPERIOD @"0123456789."

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

{

NSCharacterSet *cs;

cs = [[NSCharacterSet characterSetWithCharactersInString:ALPHANUM] invertedSet];

NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];

BOOL basicTest = [string isEqualToString:filtered];

// Add any predicate testing here

return basicTest;

}