SwiftUI:使用 anchor 调用 scrollTo 方法时崩溃:.center

Question

不能 100% 确定它是否是由 anchor 引起的因为我刚刚删除它并且到目前为止还没有遇到崩溃(如果发生更多崩溃会报告回来) - 有人可以检查并帮助看看这是否真的可能是错误所在吗？还要提交Apple错误。
我的观点是这样的:

var body: some View {
    ScrollViewReader { scrollProxy in
        ScrollView {
            if isShowingContent {
                LazyVStack {
                    ForEach(mo.msgMos.indices, id: \.self) { i in
                        ...
                    }
                }
            }
        }
        .onChange(of: mo.scrollToIdx) { idx in
            withAnimation {
                scrollProxy.scrollTo(targetIdx, anchor: .center)
            }
        }
    }
}

崩溃堆栈如下所示:

Crashed: com.apple.main-thread
0  AttributeGraph                 0x1cedce974 AGGraphGetValue + 284
1  SwiftUI                        0x1addcbe5c _ViewCache.layout.getter + 52
2  SwiftUI                        0x1addcc2f4 _ViewCache.withPlacementData<A>(_:) + 160
3  SwiftUI                        0x1addd02d0 closure #1 in IncrementalScrollable.makeTarget(at:anchor:) + 336
4  SwiftUI                        0x1addd6a9c partial apply for closure #1 in IncrementalScrollable.makeTarget(at:anchor:) + 56
5  SwiftUI                        0x1ae2241fc HostingScrollView.updateAnimationTarget(_:) + 216
6  SwiftUI                        0x1ae2245c4 HostingScrollView.bounds.didset + 188
7  SwiftUI                        0x1ae2244e8 HostingScrollView.bounds.setter + 128
8  SwiftUI                        0x1ae22444c @objc HostingScrollView.bounds.setter + 44
9  UIKitCore                      0x1aa494e4c -[UIScrollView setContentOffset:] + 804
10 UIKitCore                      0x1aa48f1e0 -[UIScrollViewScrollAnimation setProgress:] + 320
11 UIKitCore                      0x1a95094b8 -[UIAnimator _advanceAnimationsOfType:withTimestamp:] + 276
12 QuartzCore                     0x1aa8e46a4 CA::Display::DisplayLink::dispatch_items(unsigned long long, unsigned long long, unsigned long long) + 664
13 QuartzCore                     0x1aa9bb1a0 display_timer_callback(__CFMachPort*, void*, long, void*) + 280
14 CoreFoundation                 0x1a7633ce4 __CFMachPortPerform + 176
15 CoreFoundation                 0x1a7658098 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 60
16 CoreFoundation                 0x1a7657440 __CFRunLoopDoSource1 + 596
17 CoreFoundation                 0x1a7651320 __CFRunLoopRun + 2360
18 CoreFoundation                 0x1a76504bc CFRunLoopRunSpecific + 600
19 GraphicsServices               0x1be0d5820 GSEventRunModal + 164
20 UIKitCore                      0x1a9ff4734 -[UIApplication _run] + 1072
21 UIKitCore                      0x1a9ff9e10 UIApplicationMain + 168
22 Fablur                         0x102453f8c main + 12 (AppDelegate.swift:12)
23 libdyld.dylib                  0x1a7317e60 start + 4

Answer 1

我发现如果你使用 带 anchor 的 scrollTo 并将 ScrollView 的内容定位到通常无法通过正常滚动到达的位置，然后在删除 View 时它会崩溃。
例如。滚动到 ScrollView 中的最后一个 View 并使用 .leading 或 .center 位置。
我通过在 ScrollView 的末尾添加一个空白 View 来解决这个问题。不理想但有效。