Try:

NSComparisonResult order = [[UIDevice currentDevice].systemVersion compare: @"3.1.3" options: NSNumericSearch];
if (order == NSOrderedSame || order == NSOrderedDescending) {
    // OS version >= 3.1.3
} else {
    // OS version < 3.1.3
}

#define _kisiOS7 ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)

if (_kisiOS7) {
            NSLog(@"iOS7 or greater")
} 
else {
           NSLog(@"Less than iOS7");
}

Try:

NSComparisonResult order = [[UIDevice currentDevice].systemVersion compare: @"3.1.3" options: NSNumericSearch];
if (order == NSOrderedSame || order == NSOrderedDescending) {
    // OS version >= 3.1.3
} else {
    // OS version < 3.1.3
}

我的解决方案是向您的实用程序类(提示提示)添加一个实用程序方法来解析系统版本并手动补偿浮点数排序。

此外，这段代码相当简单，所以我希望它能帮助一些新手。简单地传入一个目标浮点数，然后返回BOOL类型。

在你的共享类中这样声明它:

(+) (BOOL) iOSMeetsOrExceedsVersion:(float)targetVersion;

这样叫它:

BOOL shouldBranch = [SharedClass iOSMeetsOrExceedsVersion:5.0101];

(+) (BOOL) iOSMeetsOrExceedsVersion:(float)targetVersion {

/*
 Note: the incoming targetVersion should use 2 digits for each subVersion --

 example 5.01 for v5.1, 5.11 for v5.11 (aka subversions above 9), 5.0101 for v5.1.1, etc.
*/

// Logic: as a string, system version may have more than 2 segments (example: 5.1.1)
// so, a direct conversion to a float may return an invalid number
// instead, parse each part directly

NSArray *sysVersion = [[UIDevice currentDevice].systemVersion componentsSeparatedByString:@"."];
float floatVersion = [[sysVersion objectAtIndex:0] floatValue];
if (sysVersion.count > 1) {
    NSString* subVersion = [sysVersion objectAtIndex:1];
    if (subVersion.length == 1)
        floatVersion += ([[sysVersion objectAtIndex:1] floatValue] *0.01);
    else
        floatVersion += ([[sysVersion objectAtIndex:1] floatValue] *0.10);
}
if (sysVersion.count > 2) {
    NSString* subVersion = [sysVersion objectAtIndex:2];
    if (subVersion.length == 1)
        floatVersion += ([[sysVersion objectAtIndex:2] floatValue] *0.0001);
    else
        floatVersion += ([[sysVersion objectAtIndex:2] floatValue] *0.0010);
}

if (floatVersion  >= targetVersion) 
    return TRUE;

// else
return FALSE;
 }

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。

试试这个

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7) { 
// do some work
}