heightForRowAtIndexPath间歇性地崩溃
我有一个约30个活跃用户和500多个注册用户的应用程序，这个问题只发生在一个使用iPhone 6的9.2上。
从崩溃报告中我可以看到，她已经有60多起车祸，她曾经说过这个问题有时候可以，而不是其他的。
我在这里有相同的testing设备，没有问题发生。
我不能从织物的崩溃报告详细信息中得到很多，但崩溃发生在下面的方法和应用程序崩溃在这个方法的最后其他方面，我可以从她的问题的描述：
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat { let bounds = UIScreen.mainScreen().bounds var screenWidth = bounds.size.width let screenHeight = bounds.size.height if indexPath.row == 0 { let font = UIFont(name: "Helvetica Neue", size: 17.0) let heightCalc = heightForView(self.postDescription!, font: font!, width: screenWidth - 32) if self.photoWidth != nil{ let imageAspectRatio = self.photoWidth!/self.photoHeight! var imageViewFrameHeight = screenWidth/imageAspectRatio if self.portBool { if imageViewFrameHeight > (screenHeight - 64) { screenWidth = screenWidth * 0.60 imageViewFrameHeight = imageViewFrameHeight * 0.60 } } return imageViewFrameHeight + 136 + heightCalc + 26 //return 557 } else{ return 136 + heightCalc + 30 } } else if indexPath.row == 1 { return 50.0 } else if indexPath.row == 2{ return 40.0 } else{ if self.commentsDetailed != nil && self.commentsDetailed!.count >= (indexPath.row - 3) { let commentsDetailed = self.commentsDetailed![indexPath.row-3] let font = UIFont(name: "Helvetica Neue", size: 14.0) let heightCalc = heightForView(commentsDetailed.comment!, font: font!, width: screenWidth - 51) if commentsDetailed.authorId == Prefs.userId.description { return 45 + heightCalc + 40 + 30 //return 131.5 } else{ return 45 + heightCalc + 40 //return 101.5 } } else { return 80.0 } } } 对于那些想知道的，我需要计算的高度，以避免使用表格视图自动尺寸时发生的不安的卷轴。 所以我只需要在这里解决问题而不是切换方法。
crashlytics的一些信息：
EXC_BREAKPOINT Thread : Crashed: Thread 0 ProjectName 0x10008a64c specialized NewFeedDetailedController.tableView(UITableView, heightForRowAtIndexPath : NSIndexPath) -> CGFloat (NewFeedDetailedController.swift) 1 ProjectName 0x100085258 @objc NewFeedDetailedController.tableView(UITableView, heightForRowAtIndexPath : NSIndexPath) -> CGFloat (NewFeedDetailedController.swift) 2 UIKit 0x187683638 __66-[UISectionRowData refreshWithSection:tableView:tableViewRowData:]_block_invoke + 396 3 UIKit 0x187641818 -[UISectionRowData refreshWithSection:tableView:tableViewRowData:] + 3948 4 UIKit 0x1876407d4 -[UITableViewRowData rectForFooterInSection:heightCanBeGuessed:] + 412 5 UIKit 0x187640590 -[UITableViewRowData heightForTable] + 64 6 UIKit 0x18764039c -[UITableView _updateContentSize] + 220 7 UIKit 0x1878a6f60 -[UITableView _rebuildGeometry] + 44 8 UIKit 0x1876462c8 -[UITableView didMoveToWindow] + 144 9 UIKit 0x18755705c -[UIView(Internal) _didMoveFromWindow:toWindow:] + 1496 10 UIKit 0x18757c568 -[UIScrollView _didMoveFromWindow:toWindow:] + 92 11 UIKit 0x187556d7c -[UIView(Internal) _didMoveFromWindow:toWindow:] + 760 12 UIKit 0x187556310 __45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke + 152 13 Foundation 0x183189500 -[NSISEngine withBehaviors:performModifications:] + 168 14 UIKit 0x187556194 -[UIView(Hierarchy) _postMovedFromSuperview:] + 532 15 UIKit 0x187563b80 -[UIView(Internal) _addSubview:positioned:relativeTo:] + 1784 16 UIKit 0x187755600 -[_UIParallaxDimmingView didMoveToWindow] + 180 17 UIKit 0x18755705c -[UIView(Internal) _didMoveFromWindow:toWindow:] + 1496 18 UIKit 0x187556d7c -[UIView(Internal) _didMoveFromWindow:toWindow:] + 760 19 UIKit 0x187556310 __45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke + 152 20 Foundation 0x183189500 -[NSISEngine withBehaviors:performModifications:] + 168 21 UIKit 0x187556194 -[UIView(Hierarchy) _postMovedFromSuperview:] + 532 22 UIKit 0x187563b80 -[UIView(Internal) _addSubview:positioned:relativeTo:] + 1784 23 UIKit 0x1877f5db4 __53-[_UINavigationParallaxTransition animateTransition:]_block_invoke_2 + 1656 24 UIKit 0x18756a964 +[UIView(Animation) performWithoutAnimation:] + 80 25 UIKit 0x187755118 __53-[_UINavigationParallaxTransition animateTransition:]_block_invoke + 260 26 UIKit 0x187870840 +[UIView(Internal) _performBlockDelayingTriggeringResponderEvents:] + 220 27 UIKit 0x187754c90 -[_UINavigationParallaxTransition animateTransition:] + 1060 28 UIKit 0x18770e6a0 -[UINavigationController _startCustomTransition:] + 3544 29 UIKit 0x18761a9b8 -[UINavigationController _startDeferredTransitionIfNeeded:] + 688 30 UIKit 0x18761a694 -[UINavigationController __viewWillLayoutSubviews] + 60 31 UIKit 0x18761a5fc -[UILayoutContainerView layoutSubviews] + 208 32 UIKit 0x187557778 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 656 33 QuartzCore 0x184f66b2c -[CALayer layoutSublayers] + 148 34 QuartzCore 0x184f61738 CA::Layer::layout_if_needed(CA::Transaction*) + 292 35 QuartzCore 0x184f615f8 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 32 36 QuartzCore 0x184f60c94 CA::Context::commit_transaction(CA::Transaction*) + 252 37 QuartzCore 0x184f609dc CA::Transaction::commit() + 512 38 UIKit 0x18754dc78 _afterCACommitHandler + 180 39 CoreFoundation 0x182820588 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 32 40 CoreFoundation 0x18281e32c __CFRunLoopDoObservers + 372 41 CoreFoundation 0x18281e75c __CFRunLoopRun + 928 42 CoreFoundation 0x18274d680 CFRunLoopRunSpecific + 384 43 GraphicsServices 0x183c5c088 GSEventRunModal + 180 44 UIKit 0x1875c4d90 UIApplicationMain + 204 45 ProjectName 0x1001663b0 main (AppDelegate.swift:21) 46 libdyld.dylib 0x1822ee8b8 start + 4
和heightForViewfunction：
func heightForView(text:String, font:UIFont, width:CGFloat) -> CGFloat{ let label:UILabel = UILabel(frame: CGRectMake(0, 0, width, CGFloat.max)) label.numberOfLines = 0 label.lineBreakMode = NSLineBreakMode.ByWordWrapping label.font = font label.text = text label.sizeToFit() return label.frame.height }
更新的代码检查为零，仍然崩溃的用户：
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat { let bounds = UIScreen.mainScreen().bounds var screenWidth = bounds.size.width let screenHeight = bounds.size.height if indexPath.row == 0 { CLSLogv("crashing in indexPath.Row = 0 %@", getVaList(["returning 50.0 here"])) let font = UIFont(name: "Helvetica Neue", size: 17.0) if let description = self.postDescription { let heightCalc = heightForView(description, font: font!, width: screenWidth - 32) if self.photoWidth != nil && self.photoHeight != nil { CLSLogv("crashing in indexPath.Row = 0 %@", getVaList(["inside photowidth is not nil"])) let imageAspectRatio = self.photoWidth!/self.photoHeight! var imageViewFrameHeight = screenWidth/imageAspectRatio if self.portBool { if imageViewFrameHeight > (screenHeight - 64) { screenWidth = screenWidth * 0.60 imageViewFrameHeight = imageViewFrameHeight * 0.60 } } return imageViewFrameHeight + 136.0 + heightCalc + 26.0 //return 557 } else{ CLSLogv("crashing in indexPath.Row = 0 %@", getVaList(["when photowidth is nil"])) return 136.0 + heightCalc + 30.0 } } else{ CLSLogv("crashing in indexPath.Row = 0 %@", getVaList(["unable to unwrap self.postDescription"])) if self.photoWidth != nil && self.photoHeight != nil { let imageAspectRatio = self.photoWidth!/self.photoHeight! var imageViewFrameHeight = screenWidth/imageAspectRatio if self.portBool { if imageViewFrameHeight > (screenHeight - 64) { screenWidth = screenWidth * 0.60 imageViewFrameHeight = imageViewFrameHeight * 0.60 } } return imageViewFrameHeight + 136.0 + 26.0 } else{ return 136.0 + 30.0 } } } else if indexPath.row == 1 { CLSLogv("crashing in indexPath.Row = 1 %@", getVaList(["returning 50.0 here"])) return 50.0 } else if indexPath.row == 2 { CLSLogv("crashing in indexPath.Row = 2 %@", getVaList(["returning 40.0 here"])) return 40.0 } else{ if self.commentsDetailed != nil && self.commentsDetailed!.count > (indexPath.row - 3) { if let commentsDetailed = self.commentsDetailed?[indexPath.row-3]{ let font = UIFont(name: "Helvetica Neue", size: 14.0) if let comment = commentsDetailed.comment{ let heightCalc = heightForView(comment, font: font!, width: screenWidth - 51) if commentsDetailed.authorId == Prefs.userId.description { return 45.0 + heightCalc + 40.0 + 30.0 } else{ return 45.0 + heightCalc + 40.0 } } else{ if commentsDetailed.authorId == Prefs.userId.description { return 45.0 + 40.0 + 30.0 } else{ return 45.0 + 40.0 } } } else { CLSLogv("in the else for defining commentsDetailed %a",getVaList(["commentsdetailed"])) return 80.0 } } else { CLSLogv("in the condition for checking commentsDetailed = nil - true %a", getVaList(["CRASH RELATED TO RETURNING 80 IF ARRAY IS NIL?"])) return 80.0 } } }
我认为第二个人可能会失败的唯一可能的地方是commentsDetailed.comment! 展开，如果等于零，将会失败。 其余的看起来非常健壮，包括heightForView方法。 如果检查commentsDetailed.comment != nil没有办法，我会开始认为这是一些随机9.2早期的bug …
这个错误是在最后一个闭包中popup的，就像你说的那样：
if self.commentsDetailed != nil && self.commentsDetailed!.count >= (indexPath.row - 3) { let commentsDetailed = self.commentsDetailed![indexPath.row-3]
例如，如果数组的大小为1，那么您可以索引的最后一个元素是arr [0]，但是count> =（indexPath.row – 3）会让arr [1]索引，这会导致错误。
还有其他的修复，你可以做优化，因为这个方法被重复调用。 （我build议也许有外部的字体和其他variables，这样它就不会每次都创build它们，可能有这样的优化，但我不确定）。
我不得不重新写整个游乐场find问题，所以我想我只是将代码粘贴在这里:)
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat { var screenWidth = UIScreen.mainScreen().bounds.size.width let screenHeight = UIScreen.mainScreen().bounds.size.height switch indexPath.row { case 0: guard let font = UIFont(name: "Helvetica Neue", size: 17.0) else { print("Font not Found !") break } let heightCalc = heightForView(self.postDescription! ?? "", font: font, width: screenWidth - 32) guard let photoWidth = self.photoWidth, let photoHeight = self.photoHeight else { return 136 + heightCalc + 30 } let imageAspectRatio = photoWidth / photoHeight var imageViewFrameHeight = screenWidth / imageAspectRatio if self.portBool { if imageViewFrameHeight > (screenHeight - 64) { screenWidth = screenWidth * 0.60 imageViewFrameHeight = imageViewFrameHeight * 0.60 } } return imageViewFrameHeight + 136 + heightCalc + 26 //return 557 case 1: return 50.0 case 2: return 40.0 case _ where self.commentsDetailed != nil && indexPath.row >= 3: let index = indexPath.row - 3 //I think your problem was here (your index can not be equal to the count!) guard let detailed = self.commentsDetailed where detailed.count > index else { break } let commentsDetailed = detailed[index] guard let font = UIFont(name: "Helvetica Neue", size: 14.0) else { break //font not found } let heightCalc = heightForView(commentsDetailed.comment! ?? "", font: font, width: screenWidth - 51) if commentsDetailed.authorId == Prefs.userId.description { //make sure author id is always string. sounds like a number return 45 + heightCalc + 40 + 30 //return 131.5 } else{ return 45 + heightCalc + 40 //return 101.5 } default: return 80.0 } }
你的代码中仍然有一点不一致。 尝试区分self.comentsDetailed和comentsDetailed在你的代码。 尝试为本地值select另一个名称let cd = self.commentsDetailed![indexPath.row-3]作为示例，然后在下一个语句中需要使用此值。 这可以帮助你看到你的代码中发生了什么错误。