IOS开发之不同版本适配问题2(#ifdef __IPHONE_7_0)

继续说说ios不同版本之间的适配

先说一个东西：在xcode当中有一个东西叫targets，苹果的官方文档是这样说的：

A target specifies a product to build and contains the instructions for building the product from a set of files in a project or workspace. A target defines a single product; it organizes the inputs into the build system—the source files and instructions for processing those source files—required to build that product. Projects can contain one or more targets, each of which produces one product.(省略若干字)

简单翻译过来就是一个target详细说明了要构建的产品，包含了一个工程或工作目录中的文件当中的指令，貌似还是不太清楚。在谷歌搜了一下，发现这个关于target的解释还是不错的：

A target basically defines what it is you are building and how you are building it. You can add more targets if you would like to build more than one thing. This usually makes sense if you need to build several related things from the same project. For instance, you might want one target for a full, paid version of an application, and another target for a reduced, free version of an application. Both targets would include much of the same code and resources, but some of the settings would be different and you might have different files included with each. 

意思就是如果你想将一个应用分为付费完整版和免费简化版，这两个版本大部分代码是一样的，只有个别的设置和包含的文件不同，你就可以建一个application然后弄两个targets分别对应两个版本。

下面举个简单的例子来说明在iOS7.0和iOS6.1(以及更低版本)之间的适配问题(用的是xcode5.0，里边有6.1和7.0两个版本的sdk)

新建一个工程，默认的development target，base sdk以及模拟器的版本都是7.0，在AppDelegate中的didFinishLaunchingWithOptions方法里写下

        self.window.tintColor = [UIColor redColor];

也就是说tintColor属性在iOS6.1中根本就没有，在编译时候就会出错。这时候如下加上判断语句也是没有用的，照样报错

    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0) {
        self.window.tintColor = [UIColor redColor];
    }

#ifdef __IPHONE_7_0
    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0) {
        self.window.tintColor = [UIColor redColor];
    }
#endif

#define __IPHONE_2_0     20000
#define __IPHONE_2_1     20100
#define __IPHONE_2_2     20200
#define __IPHONE_3_0     30000
#define __IPHONE_3_1     30100
#define __IPHONE_3_2     30200
#define __IPHONE_4_0     40000
#define __IPHONE_4_1     40100
#define __IPHONE_4_2     40200
#define __IPHONE_4_3     40300
#define __IPHONE_5_0     50000
#define __IPHONE_5_1     50100
#define __IPHONE_6_0     60000
#define __IPHONE_6_1     60100
#define __IPHONE_NA      99999  /* not available */

#define __IPHONE_7_0     60100

原文：http://blog.csdn.net/zwf_apple/article/details/21649397