uialertview在ios9中的使用

- (void)loginOut
{
    // 1.创建一个alertController来管理警示窗口, 并指定样式
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"确定注销吗?" message:nil preferredStyle:UIAlertControllerStyleActionSheet];
    // 2.创建点击行为, 在block中实现事件
    UIAlertAction *action = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDestructive handler:^(UIAlertAction * _Nonnull action) {
        [self.navigationController popViewControllerAnimated:YES];
        NSLog(@"已注销");
    }];
    UIAlertAction *cancel = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        NSLog(@"取消注销");
    }];
    // 3.为alertController添加点击行为
    [alertController addAction:action];
    [alertController addAction:cancel];
    // 4.弹出警示窗口
    [self presentViewController:alertController animated:YES completion:nil];
}