关于3D Touch的教程网上已经很多了，总要写点不一样的地方。本文主要是实习类似于微信带标题的PreviewingView。效果如下：

Screen Shot 2016-03-11 at 上午9.13.34.png

代码地址(Objective-C & Swift)：https://github.com/Xigtun/3DTouchdemo.git

思路大体如下：
1、轻按，在PreviewingView展示时，加上titleLabel，并使目标view向下偏移。
2、重按，进入目标控制器，移除titleLabel，并使目标view的frame恢复正常。

其他细节：有些应用没有开启的时候(被kill掉)，在桌面选择quickAction仍能进入正常的页面，有些则是启动到首页。前者是在AppDelegate获取到rootViewController，后者可能就如本例中发送通知了。

- (void)application:(UIApplication *)application performActionForShortcutItem:(UIApplicationShortcutItem *)shortcutItem completionHandler:(void (^)(BOOL))completionHandler
{
//亦可在此获取rootViewController进行操作
    [[NSNotificationCenter defaultCenter] postNotificationName:@"shortcutItemTouched" object:shortcutItem.type];
}

主要代码如下：
AppDelegate:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    [self setTouchShortcut];
    return YES;
}

- (void)setTouchShortcut
{
    UIApplicationShortcutItem *firstItem = [[UIApplicationShortcutItem alloc] initWithType:@"Red" localizedTitle:@"Red Title" localizedSubtitle:@"Red Descibe" icon:[UIApplicationShortcutIcon iconWithType:UIApplicationShortcutIconTypeDate] userInfo:nil];
    UIApplicationShortcutItem *secondItem = [[UIApplicationShortcutItem alloc] initWithType:@"Yellow" localizedTitle:@"Yellow Title" localizedSubtitle:@"Yellow Describe" icon:[UIApplicationShortcutIcon iconWithType:UIApplicationShortcutIconTypeHome] userInfo:nil];
    UIApplicationShortcutItem *thirdItem = [[UIApplicationShortcutItem alloc] initWithType:@"Blue" localizedTitle:@"Blue Title" localizedSubtitle:@"Blue Describe" icon:[UIApplicationShortcutIcon iconWithType:UIApplicationShortcutIconTypeLove] userInfo:@{@"name":@"haha"}];
    
    //haha
    NSArray *items = @[firstItem, secondItem, thirdItem];
    [UIApplication sharedApplication].shortcutItems = items;
}

- (void)application:(UIApplication *)application performActionForShortcutItem:(UIApplicationShortcutItem *)shortcutItem completionHandler:(void (^)(BOOL))completionHandler
{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"shortcutItemTouched" object:shortcutItem.type];
}

ViewController:

#pragma mark - UIViewControllerPreviewingDelegate
- (UIViewController *)previewingContext:(id<UIViewControllerPreviewing>)previewingContext viewControllerForLocation:(CGPoint)location
{
    NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:location];
    UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
    NSString *controllerTitle = self.cellTitles[indexPath.row];
    DetailViewController *detailController = [[DetailViewController alloc] initWithIdentifier:controllerTitle];
    previewingContext.sourceRect = cell.frame;
    
    UILabel *titleView = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(detailController.view.frame), 35)];
    titleView.text = controllerTitle;
    titleView.textAlignment = NSTextAlignmentCenter;
    titleView.backgroundColor = [UIColor whiteColor];
    titleView.tag = 1234;
    [detailController.view addSubview:titleView];

    return detailController;
}

- (void)previewingContext:(id<UIViewControllerPreviewing>)previewingContext commitViewController:(UIViewController *)viewControllerToCommit
{
    for (UILabel *label in viewControllerToCommit.view.subviews) {
        if (label.tag == 1234) {
            [label removeFromSuperview];
        }
    }

    [self showViewController:viewControllerToCommit sender:self];
}

DetailViewController:

- (NSArray<id<UIPreviewActionItem>> *)previewActionItems
{
    UIPreviewAction *actionOne = [UIPreviewAction actionWithTitle:@"Action One" style:UIPreviewActionStyleDefault handler:^(UIPreviewAction * _Nonnull action, UIViewController * _Nonnull previewViewController) {
        
    }];
    UIPreviewAction *actionTwo = [UIPreviewAction actionWithTitle:@"Action Two" style:UIPreviewActionStyleSelected handler:^(UIPreviewAction * _Nonnull action, UIViewController * _Nonnull previewViewController) {
        
    }];
    UIPreviewAction *actionThree = [UIPreviewAction actionWithTitle:@"Action Three" style:UIPreviewActionStyleDestructive handler:^(UIPreviewAction * _Nonnull action, UIViewController * _Nonnull previewViewController) {
        
    }];
    
    return @[actionOne, actionTwo, actionThree];
}