unity打包ios過大，ios壓縮技巧[轉]

以前每一個版本的ipa包打出來都才20M出頭，後來不知道從哪一個版本起打的包每次都將近40M，可是工程中也沒有明顯的增長很大第三方類或者圖

片、靜態文件。因而就開始了各類瘦身計劃：壓縮圖片，刪除沒必要要靜態庫。作了一番改動後發現包只比原來小了1M多，收效甚微。後來聽同事說了

armv6 armv7 armv7s arm64引發編譯包翻倍增大的問題，因而就試了一下，果真ipa包又回到了之前的大小。下邊來講一下關於iOS這個指令集(一下內容

引子DevDiv社區jas，內容稍有修改)。

 

目前ios的指令集有如下幾種：

• armv6
  • iPhone
  • iPhone2
  • iPhone3G
  • 第一代和第二代iPod Touch
• armv7
  • iPhone4
  • iPhone4S
• armv7s
  • iPhone5
  • iPhone5C
• arm64
  • iPhone5S

 機器對指令集的支持是向下兼容的，所以armv7的指令集是能夠運行在iphone5S的，只是效率沒那麼高而已~

在xcodeTARGETS裏邊Architectures:

Architecture ： 指你想支持的指令集。

Valid architectures : 指即將編譯的指令集。

Build Active Architecture Only : 只是否只編譯當前適用的指令集。

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 如今是2014年初，其實4和4S的用戶仍是蠻多的，而iphone3之類的機器幾乎沒有了，因此咱們的指令集最低必須基於armv7.

所以,Architecture的值選擇：armv7 armv7s arm64

PS:選arm64時須要最低支持5.1.1:

Convert Your App to a 64-Bit Binary After Updating It for iOS 7

Xcode 5.0.1 can build your app with both 32-bit and 64-bit binaries included. This combined binary requires a minimum deployment target of iOS 5.1.1 or later. The 64-bit binary runs only on 64-bit devices running iOS 7.0.3 and later. If you have an existing app, you should first update your app for iOS 7 and then port it to run on 64-bit processors. By updating it first for iOS 7, you can remove deprecated code paths and use modern practices. If you’re creating a new app, target iOS 7 and compile 32-bit and 64-bit versions of your app.

The architecture for 64-bit apps on iOS is almost identical to the architecture for OS X apps, making it easy to create a common code base that runs in both operating systems. Converting a Cocoa Touch app to 64-bit follows a similar transition process as the one for Cocoa apps on OS X. Pointers and some common C types change from 32 bits to 64 bits. Code that relies on the NSInteger and CGFloat types needs to be carefully examined.

Start by building the app for the 64-bit runtime, fixing any warnings that occur as well as searching your code for specific 64-bit issues. For example:

• Make sure all function calls have a proper prototype.

• Avoid truncating 64-bit values by accidentally assigning them to a 32-bit data type.

• Ensure that calculations are performed correctly in the 64-bit version of your app.

• Create data structures whose layouts are identical in the 32-bit and 64-bit versions of your app (such as when you write a data file to iCloud).

1，若是想本身的app在各個機器都可以最高效率的運行，則須要將Build Active Architecture Only改成NO,Valid architectures選擇對應的指令集：armv7 armv7s arm64。這個會爲各個指令集編譯對應的代碼，所以最後的 ipa體積基本翻了3倍,Release版本必須NO。

2，若是想讓app體積保持最小，則現階段應該選擇Valid architectures爲armv7,這樣Build Active Architecture Only選YES或NO就無所謂了