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

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

其他回答

在我的情况下，我在这段代码中有这些错误:

CAShapeLayer *shapeLayer = [CAShapeLayer layer];
UIBezierPath *path;

path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(0, 0)];
[path addLineToPoint:CGPointMake(size*2, 0)];
[path addLineToPoint:CGPointMake(size, size*2)];
[path closePath];
[path fill];

shapeLayer.path = path.CGPath;
shapeLayer.strokeColor = [[UIColor blackColor] CGColor];
shapeLayer.fillColor = color;
shapeLayer.lineWidth = width;

[self addSublayer:shapeLayer];

经过一些思考和测试，我发现了问题——这是一个电话:

[path fill];

正如我检测到的-在我的代码中，这个调用是不必要的，因为填充将通过其他方式完成-所以我简单地删除它。

2013-12-03 06:50:40

其他人会要求你在访问核心图形上下文的地方发布代码，但我怀疑这是问题所在。这些无效的上下文0x0错误消息很常见，很容易在iOS 7中重现。事实上，我可以使用零代码的故事板重现错误。我在IB中拖动UITextField到画布上，运行应用程序，双击文本字段内。

在许多情况下，我很难认真对待无效上下文0x0错误消息。我不知道您的情况是否值得更大的关注(我同意Rob Napier的观点，这是值得研究的，特别是如果您显式地使用图形上下文)。

在我自己的项目中，我希望有一天这些错误会神奇地消失(但这一天并没有伴随着7.0.3)。

更新:在安装Xcode 5.1并瞄准iOS 7.1后，我再也不能通过双击空文本字段来重现错误。

2013-10-25 21:26:16

从模拟器卸载应用程序，并再次运行

2014-09-12 09:43:30

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

对我来说，我得到这个错误，因为我正在释放CGContextRef，如下所示:

- (void)drawRect:(CGRect)rect
{
    CGContextRef context = UIGraphicsGetCurrentContext();

    // DRAW BACKGROUND CIRCLE
    CGContextSetFillColorWithColor(context, [[UIColor gray] colorWithAlphaComponent:0.6].CGColor);
    CGContextFillEllipseInRect(context, rect);

//    CGContextRelease(context);
}

删除版本解决了这个问题

2014-08-26 17:41:33

无效上下文0x0在iOS 7.0和系统降级

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