使用上模仿UIAlertController，第一版毛坯，第二版将有更多优化
CKAlertController *alertController = [CKAlertController alertControllerWithTitle:@"提示" message:@"消息" preferredStyle:CKAlertControllerStyleAlert];
CKAlertAction *cancelAction = [CKAlertAction actionWithTitle:@"默认" style:CKAlertActionStyleCancel handler:^(CKAlertAction *action) {
}];
CKAlertAction *confirmAction = [CKAlertAction actionWithTitle:@"留言" style:CKAlertActionStyleDefault handler:^(CKAlertAction *action) { content = [alertController.textFields.firstObject text];
}];
[alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) { textField.placeholder = content; }];
[alertController addAction:cancelAction]; [alertController addAction:confirmAction];
[self presentViewController:alertController animated:YES completion:^{
}];