UIAlertController *alertController = [UIAlertController alertControllerWithTitle:nil message:@"请输入支付密码" preferredStyle:UIAlertControllerStyleAlert];
//增加取消按钮；
[alertController addAction:[UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
}]];
//增加确定按钮；
[alertController addAction:[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
//获取第1个输入框；
UITextField *userNameTextField = alertController.textFields.firstObject;
NSLog(@"支付密码 = %@",userNameTextField.text);
}]];
//定义第一个输入框；
[alertController addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {
textField.placeholder = @"请输入支付密码";
textField.secureTextEntry = YES;
}];
[self presentViewController:alertController animated:true completion:nil];