作为yasimturks解决方案的一种变体，我定义了一个函数和一些枚举值，而不是五个宏。我觉得它更优雅，但那是个人品味的问题。

用法:

if (systemVersion(LessThan, @"5.0")) ...

. h文件:

typedef enum {
  LessThan,
  LessOrEqual,
  Equal,
  GreaterOrEqual,
  GreaterThan,
  NotEqual
} Comparison;

BOOL systemVersion(Comparison test, NSString* version);

m文件:

BOOL systemVersion(Comparison test, NSString* version) {
  NSComparisonResult result = [[[UIDevice currentDevice] systemVersion] compare: version options: NSNumericSearch];
  switch (test) {
    case LessThan:       return result == NSOrderedAscending;
    case LessOrEqual:    return result != NSOrderedDescending;
    case Equal:          return result == NSOrderedSame;
    case GreaterOrEqual: return result != NSOrderedAscending;
    case GreaterThan:    return result == NSOrderedDescending;
    case NotEqual:       return result != NSOrderedSame;
  }
}

你应该在名称中添加应用程序的前缀，尤其是比较类型。

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。

试试下面的代码:

NSString *versionString = [[UIDevice currentDevice] systemVersion];

所有的答案看起来都有点太大了。 我只用:

if (SYSTEM_VERSION_GREATER_THAN(@"7.0")){(..CODE...)}
if (SYSTEM_VERSION_EQUAL_TO(@"7.0")){(..CODE...)}
if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"7.0")){(..CODE...)}
if (SYSTEM_VERSION_LESS_THAN(@"7.0")){(..CODE...)}
if (SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(@"7.0")){(..CODE...)}

当然，将@“7.0”替换为所需的操作系统版本。

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
}

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