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

在某些情况下,你可能需要包含一行#import <QuartzCore/QuartzCore.h>。

其他回答

我在自定义CALayer实现的drawInContext(..)方法中得到了这个错误。UIBezierPath尝试使用UIGraphicsGetCurrentContext(),在自定义层中默认为nil。网上的文档解释得很清楚

但是,如果你没有使用UIView对象来绘图,你必须手动使用UIGraphicsPushContext函数将一个有效的上下文推入堆栈。

下面是最终与我的注释内联工作的代码(Swift代码,但解决方案是相同的不管)

override func drawInContext(ctx: CGContext!) {  
    var path = UIBezierPath()

    // 1. Make sure you push the CGContext that was first passed into you.
    UIGraphicsPushContext(ctx)
    path.moveToPoint(CGPoint(x: 0, y: 0))
    path.addLineToPoint(CGPoint(x: 150, y: 150))
    var lineColor = UIColor.blueColor()
    lineColor.setStroke()
    path.lineWidth = 2
    path.stroke(
    // 2. Pop the context after you are done.
    UIGraphicsPopContext()
}

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>}

这有点俗气,但对我很管用。

我在UITableViewCell的init中设置了UIImageView,给它一个大小和约束。

然后在我的视图控制器的cellForRowAtIndexPath中我这样做:

let img = PFImageView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
img.setImage(withFile: nil, defaultText: message.senderUsername)
cell.profileImageView?.image = img.image

这避免了错误,在函数下面,我为UIImageView设置了实际图像。上面的代码是一个很好的默认值

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!

就像其他人在这里评论的一样,当我做以下任何一件事时,我得到了这个警告:

在空白文本框中:双击,触摸并按住,长时间单点。

这似乎只影响iOS 7.0.3

我发现了一个工作周围,警告不会被触发,如果你的纸板不是NULL。

所以我在textFieldDidBeginEditing中做了以下事情:

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

    UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
    if (pasteboard.string.length == 0) {

        pasteboard.string = @" ";

    }
}

我在iphone 4s、5和5s的iOS 7.0.3模拟器中测试了这一点,不再收到警告。我也在iphone 6和6 plus上的iOS 8模拟器中测试了这一点,但我不相信iOS 8会受到影响。

在发现这个工作之前,我经历了两天的挫折,所以我真的希望我的回答能帮助那些有同样问题的人。