UIActivityViewController直接分享文字

NSArray *activityItems = @[@"窩窩頭，一塊錢四個，嘿嘿"];
UIActivity *activity = [[UIActivity alloc]init];
NSArray *activities = @[activity];
UIActivityViewController *activityVC = [[UIActivityViewController alloc] initWithActivityItems:activityItems applicationActivities:activities];
[self.navigationController presentViewController:activityVC animated:YES completion:nil];

參考：https://www.jianshu.com/p/b8a929192f8b