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

使用nv-ios-version项目(Apache License, Version 2.0)中包含的Version类，很容易获取和比较iOS版本。下面的示例代码转储iOS版本，并检查版本是否大于或等于6.0。

// Get the system version of iOS at runtime.
NSString *versionString = [[UIDevice currentDevice] systemVersion];

// Convert the version string to a Version instance.
Version *version = [Version versionWithString:versionString];

// Dump the major, minor and micro version numbers.
NSLog(@"version = [%d, %d, %d]",
    version.major, version.minor, version.micro);

// Check whether the version is greater than or equal to 6.0.
if ([version isGreaterThanOrEqualToMajor:6 minor:0])
{
    // The iOS version is greater than or equal to 6.0.
}

// Another way to check whether iOS version is
// greater than or equal to 6.0.
if (6 <= version.major)
{
    // The iOS version is greater than or equal to 6.0.
}

项目页面:nv-ios-version TakahikoKawasaki / nv-ios-version

博客:获取并比较iOS版本在运行时与版本类 获取并比较iOS版本在运行时与版本类

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

基本上和这个想法一样https://stackoverflow.com/a/19903595/1937908但更健壮:

#ifndef func_i_system_version_field
#define func_i_system_version_field

inline static int i_system_version_field(unsigned int fieldIndex) {
  NSString* const versionString = UIDevice.currentDevice.systemVersion;
  NSArray<NSString*>* const versionFields = [versionString componentsSeparatedByString:@"."];
  if (fieldIndex < versionFields.count) {
    NSString* const field = versionFields[fieldIndex];
    return field.intValue;
  }
  NSLog(@"[WARNING] i_system_version(%iu): field index not present in version string '%@'.", fieldIndex, versionString);
  return -1; // error indicator
}

#endif

只需将上面的代码放在一个头文件中。

用法:

int major = i_system_version_field(0);
int minor = i_system_version_field(1);
int patch = i_system_version_field(2);

我总是把它们保存在Constants.h文件中:

#define IS_IPHONE5 (([[UIScreen mainScreen] bounds].size.height-568)?NO:YES) 
#define IS_OS_5_OR_LATER    ([[[UIDevice currentDevice] systemVersion] floatValue] >= 5.0)
#define IS_OS_6_OR_LATER    ([[[UIDevice currentDevice] systemVersion] floatValue] >= 6.0)
#define IS_OS_7_OR_LATER    ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)
#define IS_OS_8_OR_LATER    ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)

这是一个Swift版本的yasirmturk宏。希望它能帮助一些人

// MARK: System versionning

func SYSTEM_VERSION_EQUAL_TO(v: String) -> Bool {
    return UIDevice.currentDevice().systemVersion.compare(v, options: NSStringCompareOptions.NumericSearch) == NSComparisonResult.OrderedSame
}

func SYSTEM_VERSION_GREATER_THAN(v: String) -> Bool {
    return UIDevice.currentDevice().systemVersion.compare(v, options: NSStringCompareOptions.NumericSearch) == NSComparisonResult.OrderedDescending
}

func SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v: String) -> Bool {
    return UIDevice.currentDevice().systemVersion.compare(v, options: NSStringCompareOptions.NumericSearch) != NSComparisonResult.OrderedAscending
}

func SYSTEM_VERSION_LESS_THAN(v: String) -> Bool {
    return UIDevice.currentDevice().systemVersion.compare(v, options: NSStringCompareOptions.NumericSearch) == NSComparisonResult.OrderedAscending
}

func SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v: String) -> Bool {
    return UIDevice.currentDevice().systemVersion.compare(v, options: NSStringCompareOptions.NumericSearch) != NSComparisonResult.OrderedDescending
}

let kIsIOS7: Bool = SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO("7")
let kIsIOS7_1: Bool = SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO("7.1")
let kIsIOS8: Bool = SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO("8")
let kIsIOS9: Bool = SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO("9")