双击 UITabBarItem 可像 Twitter 应用程序一样向上滚动并重新加载

Question

如何实现双击 UITabBarItem 以便它向上滚动 UITableView，就像 Twitter 应用程序所做的那样？或者对此有任何参考，

谢谢

Answer 1

您可以跟踪上次触摸日期并与当前触摸日期进行比较。
如果差异足够小（0.7 秒），您可以将其视为双击。

使用委托方法 shouldSelectViewController 在 UITabVarController 的子类中实现此功能。

这是我正在使用的工作代码。

#import "TabBarController.h"
#import "TargetVC.h"

@interface TabBarController ()

@property(nonatomic,retain)NSDate *lastTouchDate;

@end

@implementation TabBarController

//Remeber to setup UINavigationController of each of the tabs so that its restorationIdentifier is not nil
//You can setup the restoration identifier in the IB in the identity inspector for you UIViewController or your UINavigationController
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController{
    NSString *tab = viewController.restorationIdentifier;

    if([tab isEqualToString:@"TargetVC"]){

        if(self.lastTouchDate){

            UINavigationController *navigationVC = (UINavigationController*)viewController;
            TargetVC *targetVC = (TargetVC*)navigationVC.viewControllers[0];

            NSTimeInterval ti = [[NSDate date] timeIntervalSinceDate:self.lastTouchDate];
            if(ti < 0.7f)
               [targetVC scrollToTop];

        }

        self.lastTouchDate = [NSDate date];
    }

    return YES;
}

Answer 2

您可以在选项卡栏上添加点击手势：

-(void)addTapGestureOnTabbar
{
    UITapGestureRecognizer *tap =[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(doubleTapTabbarHappend:)];
    tap.numberOfTapsRequired = 2;
    tap.delaysTouchesBegan = NO;
    tap.delaysTouchesEnded = NO;
    [_tabBarController.tabBar addGestureRecognizer:tap];
}

-(void)doubleTapTabbarHappend:(UITapGestureRecognizer *)gesture
{
    CGPoint pt = [gesture locationInView:self.tabBarController.tabBar];
    NSInteger count = self.tabBarController.tabBar.items.count;
    CGFloat itemWidth = [UIScreen mainScreen].bounds.size.width/(count*1.0);
    CGFloat temp =  pt.x/itemWidth;
    int index = floor(temp);
    if (index == kTabbarItemIndex) {
        //here to scroll up and reload 
    }
}

Answer 3

可以看到 UITabBarItem (QMUI) 的代码 在 QMUI iOS，如果用户双击UITabBarItem，它支持使用块，您可以找到示例代码这里。

tabBarItem.qmui_doubleTapBlock = ^(UITabBarItem *tabBarItem, NSInteger index) {
    // do something you want...
};