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()
}

2015-01-16 18:59:43

其他回答

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

2018-09-05 15:17:33

对我来说，答案是我不必要地释放了drawRect:中的图形上下文。在CGPostError上抛出一个符号断点使我找到了罪魁祸首。

2014-04-03 22:10:10

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

UIGraphicsBeginImageContext( size );
CGContextRef context = UIGraphicsGetCurrentContext();

确定尺寸。宽度或大小。高度不为0，

你可以在CGPostError中添加符号断点来检查

2014-03-11 07:46:21

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。

2015-08-31 03:00:33

无效上下文0x0在iOS 7.0和系统降级

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