有什么方法可以检测 SDK 中支持的选项

Question

“使用基于 SDK 的开发”解释了如何使用弱链接类、方法和函数...

我用过这个例如

if ([NSByteCountFormatter class]) {
    ...
}

有没有办法检测支持的选项，例如

NSRegularExpressionSearch
The search string is treated as an ICU-compatible regular expression.
If set, no other options can apply except NSCaseInsensitiveSearch and NSAnchoredSearch.
You can use this option only with the rangeOfString:... methods and stringByReplacingOccurrencesOfString:withString:options:range:.

Available in OS X v10.7 and later.

Answer 1

用于测试一个类，例如NSUserNotificationCenter，存在，做

if(NSClassFromString(@"NSUserNotificationCenter"))
{
    //...
}

用于测试是否为常数，例如NSWindowDidChangeBackingPropertiesNotification，存在，做

BOOL NSWindowDidChangeBackingPropertiesNotificationIsAvailable = (&NSWindowDidChangeBackingPropertiesNotification != NULL);
if (NSWindowDidChangeBackingPropertiesNotificationIsAvailable) 
{
    //...
}

也请查看此答案：Check if constant is defined at runtime in Obj-C

在你的情况下，这看起来像

BOOL NSRegularExpressionSearchIsAvailable = (&NSRegularExpressionSearch != NULL);
if (NSRegularExpressionSearchIsAvailable)
{
    //...
}