{"id":599,"date":"2010-05-17T03:58:24","date_gmt":"2010-05-17T08:58:24","guid":{"rendered":"http:\/\/vgable.com\/blog\/?p=599"},"modified":"2010-05-17T03:58:29","modified_gmt":"2010-05-17T08:58:29","slug":"dont-check-for-nil-in-your-dealloc-methods","status":"publish","type":"post","link":"https:\/\/vgable.com\/blog\/2010\/05\/17\/dont-check-for-nil-in-your-dealloc-methods\/","title":{"rendered":"Don’t Check For nil in Your dealloc Methods"},"content":{"rendered":"

There’s no need to check if a variable is\u00a0nil<\/span> before\u00a0release-<\/span>ing it, because\u00a0calling a method on a NULL variable is a no-op in Objective-C<\/a>. And the runtime already has a\u00a0super-fast check for this case<\/a>.\u00a0\u00a0So adding an extra\u00a0if\u00a0test into your code will probably slow things down.<\/span><\/span><\/p>\n

Doing a pointless ”\u00a0==?nil” \u00a0test is bad for two reasons.<\/span><\/span><\/span><\/span><\/span><\/p>\n

Firstly, it’s more code<\/a> for no good reason.<\/strong> Even if it’s just one more line, It’s one more line to debug and test. It’s one more place where something could go wrong.<\/span><\/span><\/span><\/span><\/span><\/p>\n

Secondly, it’s not idiomatic Cocoa-code, so\u00a0it signals that something strange is going on.\u00a0That’s a problem for whoever is reading the code, because they have to stop and look around more carefully to figure out why the pointless tests are happening<\/em>.<\/span><\/strong><\/p>\n

In summary, do NOT do this<\/strong>:<\/p>\n

– (void<\/span>)dealloc;<\/p>\n

{<\/p>\n

<\/span><\/span>if<\/span>(<\/span>baseImage) {<\/span><\/p>\n

<\/span>[<\/span>baseImage <\/span>release<\/span>];<\/span><\/p>\n

<\/span><\/span>baseImage = <\/span>nil<\/span>;<\/span><\/p>\n

<\/span>}<\/p>\n

<\/span>[<\/span>super<\/span> <\/span>dealloc];<\/span><\/p>\n

}?<\/p>\n

Do this:<\/strong><\/p>\n

– (void<\/span>)dealloc;<\/p>\n

{<\/p>\n

<\/span>[<\/span>baseImage <\/span>release<\/span>];<\/span><\/p>\n

<\/span><\/span>baseImage = <\/span>nil<\/span>;<\/span><\/p>\n

<\/span>[<\/span>super<\/span> <\/span>dealloc];<\/span><\/p>\n

}<\/p><\/p>\n","protected":false},"excerpt":{"rendered":"

There’s no need to check if a variable is\u00a0nil before\u00a0release-ing it, because\u00a0calling a method on a NULL variable is a no-op in Objective-C. And the runtime already has a\u00a0super-fast check for this case.\u00a0\u00a0So adding an extra\u00a0if\u00a0test into your code will probably slow things down. Doing a pointless ”\u00a0==?nil” \u00a0test is bad for two reasons. Firstly, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,4],"tags":[241,106,242],"class_list":["post-599","post","type-post","status-publish","format-standard","hentry","category-cocoa","category-programming","tag-best-practices","tag-nil","tag-programming-style"],"_links":{"self":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts\/599","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/comments?post=599"}],"version-history":[{"count":1,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts\/599\/revisions"}],"predecessor-version":[{"id":600,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts\/599\/revisions\/600"}],"wp:attachment":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/media?parent=599"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/categories?post=599"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/tags?post=599"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}