怎么判断ios 版本

前几天工程项目要用到判断ios版本，最后研究了一下，分享一下：

-(void)getIOSVersion
{
// #if __IPHONE_OS_VERSION_MAX_ALLOWED >= 50000    //此方法和编译器相关
// quanju.iOSVersion=1;
// #endif
float version = [[[UIDevice currentDevice] systemVersion] floatValue]; 
if (version >= 5.0) 
{ 
quanju.iOSVersion=1;//定义全局变量标记ios版本
} 
}
-(void)getIOSModel
{
CGSize sizeToRequest;
if([[[UIDevicecurrentDevice] model] rangeOfString:@"iPad"].location== 0)
sizeToRequest = CGSizeMake(748, 110);
else
sizeToRequest = CGSizeMake(320, 48);
}
//下面是ios内其他相关信息的判断方法
获取进程信息和设备信息（包括设备类型，序列号，ios版本等）
[[NSProcessInfo processInfo] globallyUniqueString],
[[NSProcessInfo processInfo] hostName],
[[NSProcessInfo processInfo] operatingSystemName],
[[NSProcessInfo processInfo] operatingSystemVersionString],
[[NSProcessInfo processInfo] physicalMemory],
[[NSProcessInfo processInfo] processName]);
——————————————————————————————
[UIDevice currentDevice].uniqueIdentifier,
[UIDevice currentDevice].name,
[UIDevice currentDevice].systemName,
[UIDevice currentDevice].systemVersion,
[UIDevice currentDevice].model,
[UIDevice currentDevice].localizedModel,
[UIDevice currentDevice].batteryLevel
___________________________________________________
NSLog([[UIDevice currentDevice] name]); // Name of the phone as named by user
NSLog([[UIDevice currentDevice] uniqueIdentifier]); // A GUID like string
NSLog([[UIDevice currentDevice] systemName]); // "iPhone OS"
NSLog([[UIDevice currentDevice] systemVersion]); // "2.2.1"
NSLog([[UIDevice currentDevice] model]); // "iPhone" on both devices
NSLog([[UIDevice currentDevice] localizedModel]); // "iPhone" on both devices
原文地址：http://blog.csdn.net/jinglijun/article/details/7292674