ios - heightForRowAtIndexPath 间歇性崩溃

Question

我的应用程序有大约 30 个活跃用户和 500 多个注册用户，这个问题只发生在一个使用 iPhone 6 的 9.2 用户身上。

我从崩溃报告中可以看出她已经发生了 60 多次崩溃，并且她说问题有时是正常的，而其他时候则不是。

我这里有相同的测试设备，没有发生任何问题。

我无法从 fabric 的崩溃报告详细信息中获得太多信息，但崩溃发生在以下方法中，应用程序在该方法的final else 中崩溃，我可以从她对问题的描述:

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
            }

        }
    }

对于那些想知道的人，我需要计算高度以避免在我使用表格 View 自动尺寸时发生的抖动滚动。所以我只需要解决这里的问题，而不是切换方法。

来自 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 

还有 heightForView 函数:

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
    }

更新代码检查是否为 nil，但仍然会导致用户崩溃:

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
            }

        }
    }

Answer 1

我认为第二个 else 唯一可能失败的点是 commentsDetailed.comment! 展开，如果它等于 nil，它应该会失败。其余的看起来非常健壮，包括 heightForView 方法。如果检查 commentsDetailed.comment != nil 不起作用，我会开始认为这是一些随机的 9.2 早期错误...