我知道这是一个老问题，但是应该有人在available .h中提到编译时宏。这里的所有其他方法都是运行时解决方案，不能在头文件、类类别或ivar定义中工作。

对于这些情况，使用

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_14_0 && defined(__IPHONE_14_0)
  // iOS 14+ code here
#else
  // Pre iOS 14 code here
#endif

不要这样回答

UIDevice + IOSVersion.h

@interface UIDevice (IOSVersion)

+ (BOOL)isCurrentIOSVersionEqualToVersion:(NSString *)iOSVersion;
+ (BOOL)isCurrentIOSVersionGreaterThanVersion:(NSString *)iOSVersion;
+ (BOOL)isCurrentIOSVersionGreaterThanOrEqualToVersion:(NSString *)iOSVersion;
+ (BOOL)isCurrentIOSVersionLessThanVersion:(NSString *)iOSVersion;
+ (BOOL)isCurrentIOSVersionLessThanOrEqualToVersion:(NSString *)iOSVersion

@end

UIDevice + IOSVersion.m

#import "UIDevice+IOSVersion.h"

@implementation UIDevice (IOSVersion)

+ (BOOL)isCurrentIOSVersionEqualToVersion:(NSString *)iOSVersion
{
    return [[[UIDevice currentDevice] systemVersion] compare:iOSVersion options:NSNumericSearch] == NSOrderedSame;
}

+ (BOOL)isCurrentIOSVersionGreaterThanVersion:(NSString *)iOSVersion
{
    return [[[UIDevice currentDevice] systemVersion] compare:iOSVersion options:NSNumericSearch] == NSOrderedDescending;
}

+ (BOOL)isCurrentIOSVersionGreaterThanOrEqualToVersion:(NSString *)iOSVersion
{
    return [[[UIDevice currentDevice] systemVersion] compare:iOSVersion options:NSNumericSearch] != NSOrderedAscending;
}

+ (BOOL)isCurrentIOSVersionLessThanVersion:(NSString *)iOSVersion
{
    return [[[UIDevice currentDevice] systemVersion] compare:iOSVersion options:NSNumericSearch] == NSOrderedAscending;
}

+ (BOOL)isCurrentIOSVersionLessThanOrEqualToVersion:(NSString *)iOSVersion
{
    return [[[UIDevice currentDevice] systemVersion] compare:iOSVersion options:NSNumericSearch] != NSOrderedDescending;
}

@end

虽然有点晚了，但鉴于iOS 8.0的存在，这可能是相关的:

如果可以避免使用

[[UIDevice目前]系统版本]

相反，检查是否存在方法/类/其他任何东西。

if ([self.yourClassInstance respondsToSelector:@selector(<yourMethod>)]) 
{ 
    //do stuff 
}

我发现它对位置管理器很有用，我必须调用requestWhenInUseAuthorization for iOS 8.0，但该方法不适用于iOS < 8

float deviceOSVersion = [[[UIDevice currentDevice] systemVersion] floatValue];
float versionToBeCompared = 3.1.3; //(For Example in your case)

if(deviceOSVersion < versionToBeCompared)
   //Do whatever you need to do. Device version is lesser than 3.1.3(in your case)
else 
   //Device version should be either equal to the version you specified or above

在主界面轻按“设置”>常规>关于。 设备的软件版本应该出现在这个屏幕上。 检查版本号是否大于3.1.3。

以下是一个简短的版本:

struct iOSVersion {
    static let SYS_VERSION_FLOAT = (UIDevice.currentDevice().systemVersion as NSString).floatValue
    static let iOS7 = (Version.SYS_VERSION_FLOAT < 8.0 && Version.SYS_VERSION_FLOAT >= 7.0)
    static let iOS8 = (Version.SYS_VERSION_FLOAT >= 8.0 && Version.SYS_VERSION_FLOAT < 9.0)
    static let iOS9 = (Version.SYS_VERSION_FLOAT >= 9.0 && Version.SYS_VERSION_FLOAT < 10.0)
}

用法:

if iOSVersion.iOS8 {
    //Do iOS8 code here
}