drawInRect:withAttributes 因“消息发送到已释放的实例"而消失； [英] drawInRect:withAttributes dies with "message sent to deallocated instance"

问题描述

我正在为 iOS 7 更新应用程序.其中一项更改是切换到新的 drawInRect:withAttributes 函数，而不是已弃用的 drawInRect:withFont...这在 iOS 7 测试版上运行良好，但今天升级到最新的 iOS 7 版本后，应用程序崩溃了:

I am updating an app for iOS 7. One of the changes is switching to the new drawInRect:withAttributes function instead of the deprecated drawInRect:withFont... This was working fine on the iOS 7 beta, but today after upgrading to the latest iOS 7 version, the app crashes on the line:

[text drawInRect:theRect withAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIFont systemFontOfSize:fontSz], NSFontAttributeName, color, NSForegroundColorAttributeName, nil]];

随着消息:

*** -[NSStringDrawingTextStorage textContainerForAttributedString:containerSize:lineFragmentPadding:]: message sent to deallocated instance 0x187ed0f0

我尝试运行 Zombie 工具，这在我的代码中根本没有帮助，无论是分配还是释放有问题的对象.具体来说，我收到了消息:

I tried running the Zombie instrument, which is not helpful at all neither the allocation nor the release of the object in question are in my code. Specifically I get the message:

An Objective-C message was sent to a deallocated 'NSStringDrawingTextStorage' object (zombie) at address: 0x169edc50.

并且对象的 malloc/release 在调用者之下:

And the malloc/release of the object are under the caller:

[NSStringDrawingTextStorage stringDrawingTextStorage]

我做错了什么?

推荐答案

我能够通过从我渲染的 NSString 中修剪前导空格(包括换行符)来解决这个问题.这是我的分类方法:

I was able to work around this by trimming the leading whitespace (including newline characters) from the NSString I was rendering. Here's my category method:

- (NSString*)stringByTrimmingLeadingWhitespace
{
    NSUInteger index = 0;

    while((index < [self length]) && [[NSCharacterSet whitespaceAndNewlineCharacterSet] characterIsMember: [self characterAtIndex: index]])
    {
        index++;
    }

    return [self substringFromIndex: index];
}

不幸的是，如果您必须保留前导换行符，我没有其他答案.

Unfortunately if you must preserve the leading newline character(s), I do not have an alternative answer.

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