{"id":113,"date":"2014-09-22T12:41:44","date_gmt":"2014-09-22T10:41:44","guid":{"rendered":"http:\/\/blog.calj.net\/en\/?p=113"},"modified":"2014-09-22T12:41:44","modified_gmt":"2014-09-22T10:41:44","slug":"correctly-handling-dealloc-on-arm64","status":"publish","type":"post","link":"https:\/\/blog.calj.net\/en\/correctly-handling-dealloc-on-arm64\/","title":{"rendered":"Correctly handling dealloc on arm64"},"content":{"rendered":"
\"Facebook\"<\/a>\"twitter\"<\/a>\"linkedin\"<\/a>\"mail\"<\/a><\/div>

I want to share some feedback following my latest bug<\/a>: an unexplained crash which no symbolication<\/a> could help resolve.<\/p>\n

Given the following property of my City object:<\/p>\n

in City.h<\/p>\n

@property<\/span> (nonatomic<\/span>, retain<\/span>) NSString<\/span> * name;<\/pre>\n
The destructor looked like this in City.m<\/p>\n
- (void<\/span>) dealloc\r\n{\r\n\u00a0 [super<\/span> dealloc<\/span>];\r\n\u00a0 [name <\/span>release<\/span>];\r\n}\r\n<\/pre>\n
This code had worked perfectly fine on every iOS platform for years, until I compiled for the first time for t the arm64 architecture. Then it stopped to work, with an EXC_BAD_ACCESS (SIGSEGV) of subtype: KERN_INVALID_ADDRESS.<\/p>\n
Not having, initially, an iPhone 5s at hand to find where the problem was exactly, I could only rely on the crashlogs and the symbolication for arm64. Unforunately, they would not indicate anything useful.<\/p>\n
(anonymous namespace)::AutoreleasePoolPage::pop(void*) + 520\r\n_CFAutoreleasePoolPop + 24\r\n-[NSAutoreleasePool release] + 148<\/pre>\n
Well, it did talk about some release pool problem, but could never pinpoint the above section of code.<\/p>\n
It was not until I was able to use a friend’s iPhone 5s terminal, that I finally realized that the destructor should actually read like this:<\/p>\n
- (void<\/span>) dealloc\r\n{\r\n\u00a0 [name <\/span>release<\/span>];\r\n\u00a0 name<\/span> = nil<\/span>;\r\n\u00a0 [super<\/span> dealloc<\/span>];\r\n}<\/pre>\n
Calling the super prior to releasing and erase the name pointer would cause a crash on\u00a0the A7 chip in a 64-bit slice.
\nOf course, you\u00a0surely have been using ARC for a long time already, and won’t care too much about this old-stlye kind of problems. But I am not fond of managed memory, no matter the platform. I will continue to use manual memory allocation\/de- as long as the language offers to do so.<\/p>\n
Oh, and, if anyone is interested in the arm64 debug symbols for Xcode, I keep them at hand for download. Just ask me with the form below. Apple won’t like it, but I don’t like them either, so we’re even.<\/p>\n
Many thanks to @dsultan<\/a>\u00a0for his precious help & time.<\/p>\n
\u00a0! Shana Tova \u05e9\u05e0\u05d4 \u05d8\u05d5\u05d1\u05d4 !<\/h5>\n
Gabriel<\/p>\n","protected":false},"excerpt":{"rendered":"
I want to share some feedback following my latest bug: an unexplained crash which no symbolication could help resolve. Given…<\/p>\n","protected":false},"author":1,"featured_media":121,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[22,17,15,23,21,14,20,19,24],"class_list":["post-113","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ios","tag-arm64","tag-bug","tag-crash","tag-debug","tag-developer","tag-iphone","tag-memory","tag-objective-c","tag-xcode"],"_links":{"self":[{"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/posts\/113","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/comments?post=113"}],"version-history":[{"count":8,"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/posts\/113\/revisions"}],"predecessor-version":[{"id":122,"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/posts\/113\/revisions\/122"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/media\/121"}],"wp:attachment":[{"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/media?parent=113"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/categories?post=113"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.calj.net\/en\/wp-json\/wp\/v2\/tags?post=113"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}