显示操作表会导致CGContext无效上下文错误 [英] Showing actionsheet causes CGContext invalid context errors

问题描述

我正在使用操作表显示数据列表，以供用户选择。问题是使用 [self.actionSheet showInView：self.view]; 显示操作表会导致多个CGContext错误。相同的代码在iOS 6中效果很好。

I'm using actionsheet to display lists of data for the user to choose from. The problem is that showing the actionsheet using [self.actionSheet showInView:self.view]; is causing several CGContext errors. The same code worked well in iOS 6.

代码：

self.actionSheet = [[UIActionSheet alloc] initWithTitle:nil
                                             delegate:nil
                                    cancelButtonTitle:nil
                               destructiveButtonTitle:nil
                                    otherButtonTitles:nil];
[self.actionSheet setActionSheetStyle:UIActionSheetStyleBlackOpaque];

CGRect tableFrame = CGRectMake(0, 40, 320, 214);
self.tableView = [[UITableView alloc] initWithFrame:tableFrame style:UITableViewStylePlain];
self.tableView.dataSource = self;
self.tableView.delegate = self;
[self.actionSheet addSubview:self.tableView];

UISegmentedControl *closeButton = [[UISegmentedControl alloc] initWithItems:[NSArray arrayWithObject:@"Done"]];
closeButton.momentary = YES;
closeButton.frame = CGRectMake(260, 7.0f, 50.0f, 30.0f);
closeButton.tintColor = [UIColor redColor];
[closeButton addTarget:self action:@selector(dismissActionSheet:) forControlEvents:UIControlEventValueChanged];
[self.actionSheet addSubview:closeButton];

[self.actionSheet showFromView:self.view];

[UIView beginAnimations:nil context:nil];
[self.actionSheet setBounds:CGRectMake(0, 0, 320, 485)];
[UIView commitAnimations];

错误：

CGContextSetFillColorWithColor: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextSetStrokeColorWithColor: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextSetFlatness: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextAddPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextDrawPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.
CGContextRestoreGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

更新：

将cancelButtonTitle设置为@的变通办法导致我遇到此UI问题：

The workaround to set cancelButtonTitle to @"" results in this UI problem for me:

原始代码来自另一个stackoverflow答案，请参见 https://stackoverflow.com/a/2074451/654870。

The original code came from another stackoverflow answer, see https://stackoverflow.com/a/2074451/654870.

推荐答案

我相信这里的答案是UIActionSheet不能以这种方式使用，因此可能这些副作用。从 Apple ActionSheet文档， UIActionSheet并非旨在进行子类化，也不应在其层次结构中添加视图。

I believe the answer here is that UIActionSheet is not intended to be used this way, and as a result may have side effects like these. From the Apple ActionSheet documentation, "UIActionSheet is not designed to be subclassed, nor should you add views to its hierarchy."

虽然这并没有给我造成iOS 6的问题，但iOS 7却发生了一些明显的变化，我更愿意走另一条路而不是尝试与文档矛盾的东西。请注意，一种解决方法可能是为cancelButtonTitle传递@而不是nil，但这会导致其他UI问题，并且可能不会被Apple批准。

While this didn't cause problems for me in iOS 6, something has clearly changed in iOS 7 and I am more in favor of going down another route than trying to do something that contradicts the docs. Note that a workaround may be to pass @"" for the cancelButtonTitle rather than nil, but this causes other UI problems and may not be approved by Apple.

替代解决方案：

1. 创建自己的视图并以模态显示-我做了一个简单的示例项目显示了执行此操作的一种方法。


2. https://github.com/gpambrozio/BlockAlertsAnd-ActionSheets （iOS 7尚未更新）

1. Create your own view and present it modally - I made a simple example project showing one way to do this.
2. https://github.com/gpambrozio/BlockAlertsAnd-ActionSheets (no update for iOS 7 yet)

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