转自http://blog.csdn.net/zengconggen/article/details/7714514#

  开发中遇到一个问题：公司多个产品时，希望在一个产品A中可以直接打开另外的某个产品B。如果用户尚未安装产品B， 则打开app store下载页面。 对于这个问题：有3个技术点： 1、产品B是否已安装的检测。 2、应用内打开其他app的技术：参考：https://developer.apple.com/library/IOs/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/AdvancedAppTricks/AdvancedAppTricks.html#//apple_ref/doc/uid/TP40007072-CH7-SW18

 3、从应用跳转至app下载页面的技术：参考：http://blog.csdn.net/zengconggen/article/details/6789420 对于第2、3点，本文略过不讲。现提供第1技术点方案：（说明：技术有风险，有可能导致app被拒。不过app store有类似上线作品。看RP）解决方案1：(经验证：该方案真机ios5无效，模拟器可以)// Declaration  BOOL APCheckIfAppInstalled(NSString *bundleIdentifier); // Bundle identifier (eg. com.apple.mobilesafari) used to track apps    // Implementation    BOOL APCheckIfAppInstalled(NSString *bundleIdentifier)  {      static NSString *const cacheFileName = @"com.apple.mobile.installation.plist";      NSString *relativeCachePath = [[@"Library" stringByAppendingPathComponent: @"Caches"] stringByAppendingPathComponent: cacheFileName];      NSDictionary *cacheDict = nil;      NSString *path = nil;      // Loop through all possible paths the cache could be in      for (short i = 0; 1; i++)      {            switch (i) {      case 0: // Jailbroken apps will find the cache here; their home directory is /var/mobile          path = [NSHomeDirectory() stringByAppendingPathComponent: relativeCachePath];          break;      case 1: // App Store apps and Simulator will find the cache here; home (/var/mobile/) is 2 directories above sandbox folder          path = [[NSHomeDirectory() stringByAppendingPathComponent: @"../.."] stringByAppendingPathComponent: relativeCachePath];          break;      case 2: // If the app is anywhere else, default to hardcoded /var/mobile/          path = [@"/var/mobile" stringByAppendingPathComponent: relativeCachePath];          break;      default: // Cache not found (loop not broken)          return NO;          break; }            BOOL isDir = NO;          if ([[NSFileManager defaultManager] fileExistsAtPath: path isDirectory: &isDir] && !isDir) // Ensure that file exists              cacheDict = [NSDictionary dictionaryWithContentsOfFile: path];            if (cacheDict) // If cache is loaded, then break the loop. If the loop is not "broken," it will return NO later (default: case)              break;      }        NSDictionary *system = [cacheDict objectForKey: @"System"]; // First check all system (jailbroken) apps      if ([system objectForKey: bundleIdentifier]) return YES;      NSDictionary *user = [cacheDict objectForKey: @"User"]; // Then all the user (App Store /var/mobile/Applications) apps      if ([user objectForKey: bundleIdentifier]) return YES;        // If nothing returned YES already, we‘ll return NO now      return NO;  }  解决方案2：参考：http://blog.csdn.net/zengconggen/article/details/7714466本方案有限制：只能获取到用户最近运行过的app。对于已安装但是不在最近有运行的app。不适用。BOOL isExsit = [[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"rumtel://com.rumtel.AudioManager"]];  NSLog(@"App %@ installed", identifier);  if (isExsit)   {      [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"rumtel://com.rumtel.AudioManager?a=1&b=2#sect"]];  }  else  {      //打开app store下载页面  }  方案3需要知道B的打开地址。可用。最终方案确定为3附：目前公开的app相关资料：http://wiki.akosma.com/IPhone_URL_Schemes