Too many crashes about scroll to bottom

Question

I am getting too many crashes from my users for scroll to bottom. What can be cause to this problem?

I am scrolling to bottom my tableview when keyboard appears. And this causes to crash. My code:

func keyboardWillShow(notification: NSNotification) {
    var info = notification.userInfo!
    let keyboardFrame: CGRect = (info[UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue()

    self.view.layoutIfNeeded()
    UIView.animateWithDuration(0.2) {
        self.bottomCons.constant = keyboardFrame.size.height

        self.view.layoutIfNeeded()
    }
    let numberOfRows = tableView.numberOfRowsInSection(0)
    if numberOfRows != 0 {
        do {
            try tableView.scrollToRowAtIndexPath(NSIndexPath(forRow: numberOfRows-1, inSection: 0), atScrollPosition: .Bottom, animated: false) //This line is crashing
        }catch {
            print("error")
        }
    }

}

Crash log:

Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000001, 0x000000010013e018
Termination Signal: Trace/BPT trap: 5
Termination Reason: Namespace SIGNAL, Code 0x5
Terminating Process: exc handler [0]
Triggered by Thread:  0

Thread 0 name:
Thread 0 Crashed:
0   Ribony                          0x000000010013e018 specialized ChatViewController.tableView(UITableView, cellForRowAtIndexPath : NSIndexPath) -> UITableViewCell + 1904 (ChatViewController.swift:0)
1   Ribony                          0x0000000100135890 @objc ChatViewController.tableView(UITableView, cellForRowAtIndexPath : NSIndexPath) -> UITableViewCell + 76 (ChatViewController.swift:0)
2   UIKit                           0x000000018e315b58 -[UITableView _createPreparedCellForGlobalRow:withIndexPath:willDisplay:] + 716 (UITableView.m:10665)
3   UIKit                           0x000000018e315e00 -[UITableView _createPreparedCellForRowAtIndexPath:willDisplay:] + 88 (UITableView.m:10717)
4   UIKit                           0x000000018e31b4a8 -[UITableView _heightForRowAtIndexPath:] + 256 (UITableView.m:12615)
5   UIKit                           0x000000018e1127c4 -[UISectionRowData heightForRow:inSection:canGuess:] + 280 (UITableViewRowData.m:288)
6   UIKit                           0x000000018e4a413c -[UITableViewRowData ensureHeightsFaultedInForIndexPath:availHeight:edgeInset:scrollPosition:] + 1484 (UITableViewRowData.m:2418)
7   UIKit                           0x000000018e1ef4f8 -[UITableView _contentOffsetForScrollingToRowAtIndexPath:atScrollPosition:] + 1792 (UITableView.m:5544)
8   UIKit                           0x000000018e1eecb0 -[UITableView scrollToRowAtIndexPath:atScrollPosition:animated:] + 52 (UITableView.m:5644)
9   Ribony                          0x000000010013ed00 specialized ChatViewController.keyboardWillShow(NSNotification) -> () + 800 (ChatViewController.swift:550)
10  Ribony                          0x0000000100136e98 @objc ChatViewController.keyboardWillShow(NSNotification) -> () + 56 (ChatViewController.swift:0)
11  CoreFoundation                  0x00000001880b6b10 __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 20 (CFNotificationCenter.c:650)
12  CoreFoundation                  0x00000001880b6214 _CFXRegistrationPost + 400 (CFNotificationCenter.c:164)
13  CoreFoundation                  0x00000001880b5f90 ___CFXNotificationPost_block_invoke + 60 (CFNotificationCenter.c:1031)
14  CoreFoundation                  0x0000000188125b8c -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1504 (CFXNotificationRegistrar.m:163)
15  CoreFoundation                  0x0000000187ff7e64 _CFXNotificationPost + 376 (CFNotificationCenter.c:1028)
16  Foundation                      0x0000000188b2ce0c -[NSNotificationCenter postNotificationName:object:userInfo:] + 68 (NSNotification.m:482)
17  UIKit                           0x000000018e9a6b40 -[UIInputWindowController postStartNotifications:withInfo:] + 400 (UIInputWindowController.m:1375)
18  UIKit                           0x000000018e9a8cf0 __77-[UIInputWindowController moveFromPlacement:toPlacement:starting:completion:]_block_invoke.907 + 388 (UIInputWindowController.m:1816)
19  UIKit                           0x000000018e0080f0 +[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] + 636 (UIView.m:11811)
20  UIKit                           0x000000018e0d952c +[UIView(UIViewAnimationWithBlocks) _animateWithDuration:delay:options:animations:start:completion:] + 128 (UIView.m:11865)
21  UIKit                           0x000000018e9a876c -[UIInputWindowController moveFromPlacement:toPlacement:starting:completion:] + 1368 (UIInputWindowController.m:1877)
22  UIKit                           0x000000018e9af268 -[UIInputWindowController setInputViewSet:] + 1444 (UIInputWindowController.m:2923)
23  UIKit                           0x000000018e9a7e38 -[UIInputWindowController performOperations:withAnimationStyle:] + 56 (UIInputWindowController.m:1674)
24  UIKit                           0x000000018e099278 -[UIPeripheralHost(UIKitInternal) setInputViews:animationStyle:] + 1276 (UIPeripheralHost.m:4647)
25  UIKit                           0x000000018dff8a78 -[UIResponder(UIResponderInputViewAdditions) reloadInputViews] + 80 (UIResponder.m:1107)
26  UIKit                           0x000000018e056b4c -[UIResponder becomeFirstResponder] + 600 (UIResponder.m:272)
27  UIKit                           0x000000018e056ebc -[UIView(Hierarchy) becomeFirstResponder] + 148 (UIView.m:9419)
28  UIKit                           0x000000018e0d90b4 -[UITextField becomeFirstResponder] + 60 (UITextField.m:1396)
29  UIKit                           0x000000018e180128 -[UITextInteractionAssistant(UITextInteractionAssistant_Internal) setFirstResponderIfNecessary] + 192 (UITextInteractionAssistant.m:1160)
30  UIKit                           0x000000018e17f630 -[UITextInteractionAssistant(UITextInteractionAssistant_Internal) oneFingerTap:] + 3024 (UITextInteractionAssistant.m:1770)
31  UIKit                           0x000000018e59af80 -[UIGestureRecognizerTarget _sendActionWithGestureRecognizer:] + 64 (UIGestureRecognizer.m:103)
32  UIKit                           0x000000018e59e688 _UIGestureRecognizerSendTargetActions + 124 (UIGestureRecognizer.m:986)
33  UIKit                           0x000000018e16573c _UIGestureRecognizerSendActions + 260 (UIGestureRecognizer.m:1020)
34  UIKit                           0x000000018e0040f0 -[UIGestureRecognizer _updateGestureWithEvent:buttonEvent:] + 764 (UIGestureRecognizer.m:1067)
35  UIKit                           0x000000018e58e680 _UIGestureEnvironmentUpdate + 1100 (UIGestureEnvironment.m:148)
36  UIKit                           0x000000018e58e1e0 -[UIGestureEnvironment _deliverEvent:toGestureRecognizers:usingBlock:] + 408 (UIGestureEnvironment.m:1181)
37  UIKit                           0x000000018e58d49c -[UIGestureEnvironment _updateGesturesForEvent:window:] + 268 (UIGestureEnvironment.m:1090)
38  UIKit                           0x000000018e00230c -[UIWindow sendEvent:] + 2960 (UIWindow.m:2289)
39  UIKit                           0x000000018dfd2da0 -[UIApplication sendEvent:] + 340 (UIApplication.m:10729)
40  UIKit                           0x000000018e7bc75c __dispatchPreprocessedEventFromEventQueue + 2736 (UIEventDispatcher.m:1430)
41  UIKit                           0x000000018e7b6130 __handleEventQueue + 784 (UIEventDispatcher.m:1626)
42  CoreFoundation                  0x00000001880cab5c __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24 (CFRunLoop.c:1943)
43  CoreFoundation                  0x00000001880ca4a4 __CFRunLoopDoSources0 + 524 (CFRunLoop.c:1989)
44  CoreFoundation                  0x00000001880c80a4 __CFRunLoopRun + 804 (CFRunLoop.c:2821)
45  CoreFoundation                  0x0000000187ff62b8 CFRunLoopRunSpecific + 444 (CFRunLoop.c:3113)
46  GraphicsServices                0x0000000189aaa198 GSEventRunModal + 180 (GSEvent.c:2245)
47  UIKit                           0x000000018e03d7fc -[UIApplication _run] + 684 (UIApplication.m:2650)
48  UIKit                           0x000000018e038534 UIApplicationMain + 208 (UIApplication.m:4092)
49  Ribony                          0x00000001000ce070 main + 120 (AppDelegate.swift:15)
50  libdyld.dylib                   0x0000000186fd95b8 start + 4

As you can see i am using this in a try catch block. It should not crash. How is this possible?

Did you make sure that numberOfRows is not nil, or negative? — Bjørn Ruthberg, Feb 24 '17 at 08:35
you can set exception breakpoint and get the line at which your code is breaking: http://stackoverflow.com/questions/17802662/exception-breakpoint-in-xcode — viral, Feb 24 '17 at 08:39

score 0 · Answer 1 · answered Feb 24 '17 at 12:00

Try this code

func keyboardWillShow(notification: NSNotification) {
var info = notification.userInfo!
let keyboardFrame: CGRect = (info[UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue()

self.view.layoutIfNeeded()
UIView.animateWithDuration(0.2) {
    self.bottomCons.constant = keyboardFrame.size.height

    self.view.layoutIfNeeded()
        }
   tableViewScrollToBottom(true)


}

func tableViewScrollToBottom(animated: Bool) {

let delay = 0.2 * Double(NSEC_PER_SEC)
let time = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))

dispatch_after(time, dispatch_get_main_queue(), {

    let numberOfSections = self.tableView.numberOfSections()
    let numberOfRows = self.tableView.numberOfRowsInSection(numberOfSections-1)

    if numberOfRows > 0 {
        let indexPath = NSIndexPath(forRow: numberOfRows-1, inSection: (numberOfSections-1))
        self.tableView.scrollToRowAtIndexPath(indexPath, atScrollPosition: UITableViewScrollPosition.Bottom, animated: animated)
    }

})
}

Too many crashes about scroll to bottom

1 Answers1