蘋果系列：跨平台編譯的宏定義選擇(區分ios和mac)

大意：

光用TARGET_OS_MAC并不能夠區分ios和mac，需要像這樣：

#if TARGET_OS_IPHONE

#define VIEW_CLASS UIView

#elif TARGET_OS_MAC

#define VIEW_CLASS NSView

#endif

先檢查TARGET_OS_IPHONE 這個宏，在ios下（無論真機還是模拟器）該宏被定義；若未定義該宏則檢查TARGET_OS_MAC。

原文如下：

Yesterday, I was messing around building shared NSLayoutConstraint code to be used across iOS and OS X. I put in a few #if TARGET_OS_MAC directives, assuming they'd just work.

They didn't.

Turns out that you should always check for TARGET_OS_IPHONE first, before TARGET_OS_MAC because the latter is true on the iPhone but the former is not on OS X.

Here are some of the most common checks suggested to me yesterday as I messed with this dilemma.

#if TARGET_OS_MAC

#if TARGET_IPHONE_SIMULATOR

#if TARGET_OS_EMBEDDED

#if defined(__MAC_OS_X_VERSION_MIN_REQUIRED)

#if defined(__IPHONE_OS_MIN_VERSION_REQUIRED)

And here are the results of running them on the Simulator, iPhone device and OS X:

SIMULATOR

Target OS Mac

Target OS iPhone

No Target OS Embedded

Target iPhone Simulator

Mac OS X Version Min Required is NOT defined

iPhone OS X Version Min Required is NOT defined

PHONE

Target OS Embedded

No Target iPhone Simulator

OS X

No Target OS iPhone

Mac OS X Version Min Required is defined

Since I was most interested in determining whether to use NSBox/NSView vs UIView, my solution ended up looking like this:

This approach ensured that the iPhone platform triggered first, and then the second check mandated OS X. This created definitions that allowed my code to successfully compile and execute cross-platform.