无效上下文0x0在iOS 7.0和系统降级

关于这个可怕的问题，我已经阅读了尽可能多的搜索结果，不幸的是，每个搜索结果似乎都集中在一个特定的函数调用上。

我的问题是，我从多个函数得到相同的错误，我猜是从我使用的函数回调的。

更糟糕的是，实际的代码是在另一个项目中导入的自定义私有框架中，因此，调试不是那么简单吗?

有人能告诉我正确的方向吗?我有一种感觉，我正在错误地调用某些方法或与坏的上下文，但xcode的输出在这一点上不是很有帮助。

: 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. : CGContextGetBlendMode: 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.

当呈现自定义视图或其继承的类之一时，可能会发生这些错误。这时它们会生成多次，直到键盘不再提供任何输入。触摸事件仍然被注册，但是系统变慢，最终可能导致未分配对象错误。

编辑#1:我确实可以访问正在导入的框架，但我没有看到导致问题的类中有任何奇怪的东西。

编辑#2:我刚刚收到一封电子邮件，iOS 7.1已经发布给开发者了。我很好奇这种情况是否会消失，或者变得更糟，或者是否能得到解决。

当前回答

我有这个问题在一个UITextField，当我持有一个空白字段与占位符文本的触摸。我使用以下方法来消除空白字段:

-(void)textFieldDidBeginEditing:(UITextField *)textField{

        textField.text=[@" " stringByAppendingString:textField.text];

        //other stuff here
}


-(BOOL)textFieldShouldReturn:(UITextField *)textField{

         if(textField.text.length>0){
             if([[textField.text substringToIndex:1] isEqualToString:@" "])
                 textField.text=[textField.text substringFromIndex:1];
         }
         //  other stuff here
}

2014-02-17 09:03:52

其他回答

得到了我设置的错误

textfield.delegate = self

无需实现任何委托例程。去掉那条线就解决了我的问题

2014-04-15 06:03:30

I have had cases where the context returned from UIGraphicsGetCurrentContext() is NULL, and if you try using it for anything this message appears. It is the view's responsibility to push a context using UIGraphicsPushContext prior to calling drawRect:, if you call drawRect: directly instead of [view setNeedsDisplay] you risk the context not being set yet. My hunch is that prior to iOS 7 the context was pushed for the view on init, and now on iOS 7 the context isn't pushed until the first time drawRect: is about to be called. I suspect some UIKit code is calling drawRect: directly and this is why there are issues with some code even when no custom drawing is being done.

解决方案(如果做自定义绘图):

不要直接调用drawRect:，使用[view setNeedsDisplay]，或者如果你需要立即绘图，使用[view。层画) 在你的drawRect:获取上下文，但不要在if语句体之外使用if (context) {<do drawing here>}

2014-01-14 17:54:33

当我在UIActivity子类的activityImage方法中输入错误的图像名称时，我得到了它

- (UIImage *)activityImage
{
    return [UIImage imageNamed:@"img.png"];
}

输入正确的图像为我解决了这个问题。

2014-08-31 20:57:51

这些类型的错误是历史上调用核心图形函数的结果，而不是在一个上下文中建立的drawRect或调用之间，如UIGraphicsBeginImageContext和UIGraphicsEndImageContext(或其他UIKit函数，如开始和结束一个上下文)。

话虽如此，但bilobatum说的没错，这一系列错误可能是他在回答中提到的iOS 7漏洞造成的。如果在你的iOS6目标中没有看到这些错误，或者在快速扫描这个私有框架后，你没有发现任何可疑的核心图形调用，这可能只是iOS 7的错误。接得好，双叶巴坦!

2013-10-25 21:26:38

我有同样的问题，我忘记导入QuartzCore/QuartzCore.h，这解决了我的问题与这些错误。

    #import <QuartzCore/QuartzCore.h>

2014-01-31 02:32:34

无效上下文0x0在iOS 7.0和系统降级

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