unity打包ios过大，ios压缩技巧[转]

以前每一个版本的ipa包打出来都才20M出头，后来不知道从哪一个版本起打的包每次都将近40M，可是工程中也没有明显的增长很大第三方类或者图

片、静态文件。因而就开始了各类瘦身计划：压缩图片，删除没必要要静态库。作了一番改动后发现包只比原来小了1M多，收效甚微。后来听同事说了

armv6 armv7 armv7s arm64引发编译包翻倍增大的问题，因而就试了一下，果真ipa包又回到了之前的大小。下边来讲一下关于iOS这个指令集(一下内容

引子DevDiv社区jas，内容稍有修改)。

 

目前ios的指令集有如下几种：

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

 机器对指令集的支持是向下兼容的，所以armv7的指令集是能够运行在iphone5S的，只是效率没那么高而已~

在xcodeTARGETS里边Architectures:

Architecture ： 指你想支持的指令集。

Valid architectures : 指即将编译的指令集。

Build Active Architecture Only : 只是否只编译当前适用的指令集。

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 如今是2014年初，其实4和4S的用户仍是蛮多的，而iphone3之类的机器几乎没有了，因此咱们的指令集最低必须基于armv7.

所以,Architecture的值选择：armv7 armv7s arm64

PS:选arm64时须要最低支持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在各个机器都可以最高效率的运行，则须要将Build Active Architecture Only改成NO,Valid architectures选择对应的指令集：armv7 armv7s arm64。这个会为各个指令集编译对应的代码，所以最后的 ipa体积基本翻了3倍,Release版本必须NO。

2，若是想让app体积保持最小，则现阶段应该选择Valid architectures为armv7,这样Build Active Architecture Only选YES或NO就无所谓了