let device = UIDevice.currentDevice()
if (device.systemVersion.bridgeToObjectiveC().floatValue < 8.0) {
    [skipped]
}@H_403_3@ 
 
此外,不可能将字符串向下转换为浮动.
 
  
 
let device = UIDevice.currentDevice()
let version: Float = device.systemVersion as Float@H_403_3@ 
 
上面的代码段返回’String’不能转换为’Float’错误.
 
 
任何想法我们现在应该如何测试操作系统版本？谢谢.