看代碼的時候看到一句，用於獲取.plist文件的版本號

labelVersion.text = [NSString stringWithFormat:@"v%@", [[NSBundle mainBundle] objectForInfoDictionaryKey:(NSString*)kCFBundleVersionKey]];

比較感興趣的是後面的參數 kcFBundleVersionKey ,竟然是CFBundle.h已經定於好的屬性，下面有這個屬性的注釋

const CFStringRef kCFBundleVersionKey;

/* The version number of the bundle. For Mac OS 9 style version numbers (for example "2.5.3d5"), */

/* clients can use CFBundleGetVersionNumber() instead of accessing this key directly since that */

/* function will properly convert the version string into its compact integer representation. */

還有好多是kcFXXX開頭的Standard Info.plist keys 屬性，有興趣可以自己看一下CFBundle.h，研究一下它們的用法，