Too many crashes about scroll to bottom - ios

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?

Answer 1

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)
}
})
}