Show scrollbar in UITableView before the table is

问题:

In a I am using several UITableView in my app. Some of them contain several rows, while some have two three only. What I need is: if the table contains several rows, then the scrollbar should be visible before the user even drags the table down. Or in another way, is it possible to make scrollbar visible always??

回答1:

You can flash them but there isn't an option to make them always visible:

[ScrollView flashScrollIndicators];

UITableView is a subclass of UIScrollView,So you can use it directly with it

  - (void)viewDidAppear:(BOOL)animated {
      [super viewDidAppear:animated];
      [self.tableView performSelector:@selector(flashScrollIndicators) withObject:nil afterDelay:0];
}

Check out for more info : UIScrollView - showing the scroll bar

Swift:

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
    self.tableView.flashScrollIndicators()   
}

回答2:

Swift 3.0

1) Timer

var timerForShowScrollIndicator: Timer?

2) Methods

/// Show always scroll indicator in table view
func showScrollIndicatorsInContacts() {
    UIView.animate(withDuration: 0.001) {
        self.tableView.flashScrollIndicators()
    }
}

/// Start timer for always show scroll indicator in table view
func startTimerForShowScrollIndicator() {
    self.timerForShowScrollIndicator = Timer.scheduledTimer(timeInterval: 0.3, target: self, selector: #selector(self.showScrollIndicatorsInContacts), userInfo: nil, repeats: true)
}

/// Stop timer for always show scroll indicator in table view
func stopTimerForShowScrollIndicator() {
    self.timerForShowScrollIndicator?.invalidate()
    self.timerForShowScrollIndicator = nil
}

3) Use

startTimerForShowScrollIndicator in viewDidAppear

stopTimerForShowScrollIndicator in viewDidDisappear