iOS XCode啓用/關閉Clang Warnings

時間 2019-12-02

標籤 ios xcode 啓用關閉 clang warnings 欄目 iOS 简体版

原文原文鏈接

前言：warnings是編碼中很重要的一個環節，編譯器給出合理的warning能幫助開發者找到本身代碼的問題，防止不少bug產生。
默認用XCode建立一個工程，會自動開啓一些重要的warnings，可是更多的時候，咱們須要編譯器更完整的提醒。html

iOS開發採用Clang編譯器。objective-c

默認的Warning能夠在Build Settings裏找到

在search裏搜索Warnings，就能夠看到如圖,這是爲全部語言開啓的warnings
ruby

固然，也能夠爲不一樣語言開啓warning，也在Build Settings裏
app

可是，這樣一個個的開啓關閉定製化很好，有時候咱們只須要開啓所有或者開啓所有重要的warnings便可
這時候,進入

能夠添加一些build flag來啓用警告，主要的就是三個ui

1.-Wall Clang認爲本身可以準確報出的警告
2. -Wextra額外的苛刻的警告，這些警告不必定會形成錯誤。例如若是使用這個flag，把singned 賦值給unsigned就會觸發警告，而大多數時候這樣賦值是沒問題的。
3.-Weverything 全部警告this

通常的項目都是開啓-Wall和-Wextra兩個警告來保證沒有嚴重錯誤，固然，若是有些明顯的不會出錯，能夠用關閉某個或者某些警告。編碼

<code class="hljs lasso has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-attribute" style="box-sizing: border-box;">-Wall</span> <span class="hljs-attribute" style="box-sizing: border-box;">-Wno</span><span class="hljs-attribute" style="box-sizing: border-box;">-unused</span><span class="hljs-attribute" style="box-sizing: border-box;">-variable</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//啓用Wall可是剔除unused-variable</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

用語句強制開啓或者關閉某個警告

強制開啓一個警告atom

<code class="hljs cs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#<span class="hljs-keyword" style="box-sizing: border-box;">warning</span> "This method can not be used"</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

強制開啓一個錯誤spa

<code class="hljs cs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#<span class="hljs-keyword" style="box-sizing: border-box;">error</span> "You must add this key,or you will fail"</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

強制關閉一個警告
例如
這裏會出現警告test這個selector沒有實現.net

<code class="hljs ruby has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">[<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">self</span> <span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">performSelector:</span><span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@selector</span>(test) <span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">withObject:</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">nil</span>];
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

強制關閉這個警告

<code class="hljs cs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#<span class="hljs-keyword" style="box-sizing: border-box;">pragma</span> clang diagnostic push</span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#<span class="hljs-keyword" style="box-sizing: border-box;">pragma</span> clang diagnostic ignored "-Wundeclared-selector"</span>
    [self performSelector:@selector(test) withObject:nil];
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#<span class="hljs-keyword" style="box-sizing: border-box;">pragma</span> clang diagnostic pop</span>
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

經常使用的CLang Warning

Wall

Wbad-function-cast

Wcast-align

Wconversion

Wdeclaration-after-statement

Wdeprecated-implementations

Wextra

Wfloat-equal

Wformat=2

Wformat-nonliteral

Wfour-char-constants

Wimplicit-atomic-properties

Wmissing-braces

Wmissing-declarations

Wmissing-field-initializers

Wmissing-format-attribute

Wmissing-noreturn

Wmissing-prototypes

Wnested-externs

Wnewline-eof

Wold-style-definition

Woverlength-strings

Wparentheses

Wpointer-arith

Wredundant-decls

Wreturn-type

Wsequence-point

Wshadow

Wshorten-64-to-32

Wsign-compare

Wsign-conversion

Wstrict-prototypes

Wstrict-selector-match

Wswitch

Wswitch-default

Wswitch-enum

Wundeclared-selector

Wuninitialized

Wunknown-pragmas

Wunreachable-code

Wunused-function

Wunused-label

Wunused-parameter

Wunused-value

Wunused-variable

Wwrite-strings