输入框UITextField禁止输入空格

1，遵循UITextField的代理方法
2，实现代理方法

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSString *tem = [[string componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]componentsJoinedByString:@""];
    if (![string isEqualToString:tem]) {
        return NO;
    }
    return YES;
}