我想检查设备的iOS版本是否大于3.1.3 我尝试了以下方法:
[[UIDevice currentDevice].systemVersion floatValue]
但是不管用,我只想要一个:
if (version > 3.1.3) { }
我怎样才能做到这一点呢?
我想检查设备的iOS版本是否大于3.1.3 我尝试了以下方法:
[[UIDevice currentDevice].systemVersion floatValue]
但是不管用,我只想要一个:
if (version > 3.1.3) { }
我怎样才能做到这一点呢?
当前回答
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。
其他回答
/*
* System Versioning Preprocessor Macros
*/
#define SYSTEM_VERSION_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedSame)
#define SYSTEM_VERSION_GREATER_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedDescending)
#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedDescending)
/*
* Usage
*/
if (SYSTEM_VERSION_LESS_THAN(@"4.0")) {
...
}
if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"3.1.1")) {
...
}
简单的回答是……
从Swift 2.0开始,你可以在if或guard中使用#available来保护那些只能在特定系统上运行的代码。
if #available(iOS 9, *) {} 在Objective-C中,您需要检查系统版本并进行比较。
iOS 8及以上版本[[NSProcessInfo processInfo] operatingSystemVersion]。
从Xcode 9开始:
if (@available(iOS 9, *)) {}
完整的答案是……
在Objective-C和Swift中,最好避免依赖操作系统版本作为设备或操作系统功能的指示。通常有更可靠的方法来检查特定的特性或类是否可用。
检查api的存在:
例如,你可以使用NSClassFromString检查UIPopoverController在当前设备上是否可用:
if (NSClassFromString(@"UIPopoverController")) {
// Do something
}
对于弱链接的类,直接向类发送消息是安全的。值得注意的是,这适用于没有显式链接为“Required”的框架。对于缺少的类,表达式的计算结果为nil,不满足条件:
if ([LAContext class]) {
// Do something
}
一些类,如CLLocationManager和UIDevice,提供了检查设备功能的方法:
if ([CLLocationManager headingAvailable]) {
// Do something
}
检查符号的存在:
偶尔,您必须检查是否存在常数。这是在iOS 8中引入的UIApplicationOpenSettingsURLString,用于通过-openURL:加载设置应用程序。该值在iOS 8之前不存在。将nil传递给这个API会崩溃,所以你必须先注意验证这个常量的存在:
if (&UIApplicationOpenSettingsURLString != NULL) {
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
}
与操作系统版本比较:
让我们假设您需要检查操作系统版本,这种情况相对较少。对于针对iOS 8及以上版本的项目,NSProcessInfo包含了一个执行版本比较的方法,出错的几率更小:
- (BOOL)isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion)version
针对旧系统的项目可以在UIDevice上使用systemVersion。苹果在他们的GLSprite示例代码中使用了它。
// A system version of 3.1 or greater is required to use CADisplayLink. The NSTimer
// class is used as fallback when it isn't available.
NSString *reqSysVer = @"3.1";
NSString *currSysVer = [[UIDevice currentDevice] systemVersion];
if ([currSysVer compare:reqSysVer options:NSNumericSearch] != NSOrderedAscending) {
displayLinkSupported = TRUE;
}
如果出于某种原因,您决定systemVersion是您想要的,请确保将其视为字符串,否则您将冒着截断补丁版本号的风险(例如。3.1.2 -> 3.1)。
一个在obj - c++ 11中更通用的版本(你可能会用NSString/C函数替换其中的一些东西,但这不是那么冗长。这给了你两种机制。splitSystemVersion为你提供了一个包含所有部分的数组,如果你只是想打开主版本(例如switch([self splitSystemVersion][0]) {case 4: break;案例5:断裂;})。
#include <boost/lexical_cast.hpp>
- (std::vector<int>) splitSystemVersion {
std::string version = [[[UIDevice currentDevice] systemVersion] UTF8String];
std::vector<int> versions;
auto i = version.begin();
while (i != version.end()) {
auto nextIllegalChar = std::find_if(i, version.end(), [] (char c) -> bool { return !isdigit(c); } );
std::string versionPart(i, nextIllegalChar);
i = std::find_if(nextIllegalChar, version.end(), isdigit);
versions.push_back(boost::lexical_cast<int>(versionPart));
}
return versions;
}
/** Losslessly parse system version into a number
* @return <0>: the version as a number,
* @return <1>: how many numeric parts went into the composed number. e.g.
* X.Y.Z = 3. You need this to know how to compare again <0>
*/
- (std::tuple<int, int>) parseSystemVersion {
std::string version = [[[UIDevice currentDevice] systemVersion] UTF8String];
int versionAsNumber = 0;
int nParts = 0;
auto i = version.begin();
while (i != version.end()) {
auto nextIllegalChar = std::find_if(i, version.end(), [] (char c) -> bool { return !isdigit(c); } );
std::string versionPart(i, nextIllegalChar);
i = std::find_if(nextIllegalChar, version.end(), isdigit);
int part = (boost::lexical_cast<int>(versionPart));
versionAsNumber = versionAsNumber * 100 + part;
nParts ++;
}
return {versionAsNumber, nParts};
}
/** Assume that the system version will not go beyond X.Y.Z.W format.
* @return The version string.
*/
- (int) parseSystemVersionAlt {
std::string version = [[[UIDevice currentDevice] systemVersion] UTF8String];
int versionAsNumber = 0;
int nParts = 0;
auto i = version.begin();
while (i != version.end() && nParts < 4) {
auto nextIllegalChar = std::find_if(i, version.end(), [] (char c) -> bool { return !isdigit(c); } );
std::string versionPart(i, nextIllegalChar);
i = std::find_if(nextIllegalChar, version.end(), isdigit);
int part = (boost::lexical_cast<int>(versionPart));
versionAsNumber = versionAsNumber * 100 + part;
nParts ++;
}
// don't forget to pad as systemVersion may have less parts (i.e. X.Y).
for (; nParts < 4; nParts++) {
versionAsNumber *= 100;
}
return versionAsNumber;
}
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")
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