UIScrollview中的后台线程崩溃 [英] Crash in background thread in UIScrollview

问题描述

为了提高性能，我在后台线程中为滚动视图创建了子视图，然后使用performSelectorOnMainThread将事件发布到主线程，并将视图添加到其中的滚动视图中并带上字体.但是有时我会崩溃.

In order to improve performance i am creating subviews for my scroll view in a background thread and then posting the event to main thread using performSelectorOnMainThread and adding the view into the scrollview in it and bring it to font. However i get a crash sometimes.

当我在后台线程中对此进行检查时.

When i check this in my background thread.

if( nil == myView.view.superview)

如何在后台线程中安全地执行此检查线程.如果我必须在主线程上执行，那么我需要进行很多更改设计，因此我可以将其发布到主线程并使用返回值吗? 我对其他选择持开放态度.

How can i perform this check thread safe in the background thread. If i have to perform on main thread then i need to change the design a lot, hence can there be a way i post it to main thread and use the return value. I am open to alternatives on the same.

TIA，

Praveen S

Praveen S

我已经实现了分页的UIScrollview.但是，由于性能问题以及为了提高UI的响应性，我将使用创建的子视图移动到另一个线程中

I have implemented UIScrollview with paging. However due to performance issues and to improve responsiveness of the UI i moved creating the subviews into a different thread using

[self performSelectorInBackground:@selector(loadPages:) withObject:nil];

在加载页面中，我执行以下操作

In load pages, i do the following

if( nil == myView.view.superview) 
{
Create the view
 [[self performSelectorOnMainThread:@selector(refreshViews:) myView.view waitUntilDone:YES];
}

在刷新视图中，我将子视图添加到scrollview并将其置于最前面.

In refresh view i add the subview to scrollview and bring it to front.

[myScrollView addSubview:views];
[myScrollView bringSubviewToFront:views];

但是，添加和页面控件可以正常工作.滚动还可以，还可以.但是当我快速滚动它(以快速方式在屏幕上滑动)时，应用程序崩溃了.

However the get added and page control works fine. Scrolling is ok ok kind smooth. But when i scroll it fast( swipe across the screen in a fast manner) the application crashes.

调试器说，如果在加载页面中执行了if检查，则崩溃发生在obj_msgSend.

The debugger says the crash is at obj_msgSend after the if check in the loadpages.

堆栈跟踪-这次它在检查@synchronized时崩溃了.出于安全原因，我已经编辑了崩溃日志以删除项目的特定名称，但是跟踪如下.

Stack trace -- Well it crashed at the check @synchronized this time. I have edited the crash log to remove project specific names for security reasons but the trace is as below.

#0  0x33a06464 in objc_msgSend ()
#1  0x314d6984 in -[UIViewController _loadViewFromNibNamed:bundle:] ()
#2  0x314d5cb8 in -[UIViewController loadView] ()
#3  0x313d6226 in -[UIViewController view] ()
#6  0x00009920 in -[myViewController loadPages:] (self=0x12a2a0, _cmd=0x1eac1, abcd=0x0) at 
#7  0x302d9198 in -[NSThread main] ()
#8  0x302d2248 in __NSThread__main__ ()
#9  0x3110c88c in _pthread_start ()
#10 0x31101a90 in thread_start ()

推荐答案

UIKit并非线程安全的，除非另有明确标记.不支持在后台创建视图(和加载笔尖).任何涉及UIView的事情都需要在主线程上进行.即使在将视图添加到超级视图之前，这也适用.

UIKit is not thread-safe unless specifically marked otherwise. Creating views (and loading nibs) in the background is not supported; anything that touches a UIView needs to happen on the main thread. This applies even before your view has been added to a superview.

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