coacoapods中的podfile介绍；如何指定版本号(内容来自官方英文blog)

一个简单的podfile:

pod ‘AFNetworking‘, ‘~> 1.0‘ 版本号可以是1.0，可以是1.1，1.9，但必须小于2

－个更简单的podfile:

pod ‘AFNetworking‘, ‘1.0‘ // 版本号指定为1.0

一个更更简单的podfile:

pod ‘AFNetworking‘,  // 不指定版本号，任何版本都可以

一个复杂的podfile:
 

platform :ios, ‘6.0‘
inhibit_all_warnings!

xcodeproj ‘MyProject‘

pod ‘ObjectiveSugar‘, ‘~> 0.5‘

target :test do
    pod ‘OCMock‘, ‘~> 2.0.1‘
end

post_install do |installer|
    installer.project.targets.each do |target|
        puts target.name
    end
end

下面是podfile指定版本号时的逻辑运算符：
Besides no version, or a specific one, it is also possible to use logical operators:
‘> 0.1‘    Any version higher than 0.1         0.1以上
‘>= 0.1‘   Version 0.1 and any higher version  0.1以上，包括0.1
‘< 0.1‘    Any version lower than 0.1          0.1以下
‘<= 0.1‘   Version 0.1 and any lower version   0.1以下，包括0.1
In addition to the logic operators CocoaPods has an optimisic operator ~>:
‘~> 0.1.2‘ Version 0.1.2 and the versions up to 0.2, not including 0.2 and higher  0.2以下(不含0.2)，0.1.2以上（含0.1.2）
‘~> 0.1‘ Version 0.1 and the versions up to 1.0, not including 1.0 and higher      1.0以下(不含1.0)，0.1以上（含0.1）
‘~> 0‘ Version 0 and higher, this is basically the same as not having it.          0和以上，等于没有此约束