Tips: Caller ID for Phone app

The Phone app is one of the most commonly used iOS apps on the iPhone. You can find a handful of features in the Settings->Phone. For instance, you can configure your caller ID to be either shown or hidden when making a call.

However, occasionally, you might wish to display or hide your caller ID for specific individuals or businesses without having to reset this setting from the Settings menu for every single call, which can be quite laborious. Here are two tips for using the Phone app to achieve this temporarily.

Use the code #31#  before your phone number to hide your caller ID, like in this example:

Use the code *31# before your phone number to display your caller ID, like in another example:

Those codes are very easy to remember. Think of *as a star presenting you, and # as a fence hiding anything. The remaining codes are the same.

Secret Cache of WeChat

By chance, yesterday when I clicked on a message with a link to a document file in Mac's WeChat app, I was prompt to Finder. To my surprice, this is a deep and secret space where WeChat stores temporary files.

Further exploration, I found its path from file info in Finder.

From there I copied the full path from Where. Here is the full path

/Users/xxx/Library/Containers/com.tencent.xinWeChat/Data/Library/Application Support/com.tencent.xinWeChat/2.0b4.0.9/f5210b300b4abef170762c8c1ddf67c5/Message/MessageTemp/2d14efe546045554426bdf707c13cead

I understand that WeChat saves some information such as images, files, videos in local cache so that there would be no need to download those information again for displaying (and much qicker) when user clicks on thos items. However, I don't know where they are and how long those items are stored, forever?

From this sneak, I could go up to other folders to see what items are saved. There are quite a lots of items in this library cache. I guess that those items would be purgeble items in system cache.

Add Picture to PDF File

Preview is a versatile tool to view and edit various types of files, including PDF. For example, by using Preview, you can add new text, lines, object shapes to a PDF file. However, it seems, at first,  that images could not be directly added to PDF file(no ways from Previews' menu or toolbar icons), none be directly pasted to.

Just a shorting time searching from internet, I found a way to do that.  Here is the trick to do that:

1. First copy and paste an image to Preview by Ctrl+N as a new image file;
2. then select all or part of image and make a copy (Ctrl+C).
3. Paste the selection by Ctrl+V.
4. Select all again (Ctrl+A), and
5. cut the selection(Ctrl+X). This new copy will be as an object instead of image.
6. The last step is to paste the object to your PDF file in Preview by Ctrl+V!

References

• How-To Geek article: Hwo to Add An Image a PDF File with Preview

Link to a note in Notes.app

Notes.app is a very good app in Apple eco-system. You can add a note on Mac or iPhone or iCloud. Then all the notes are synced in iCloud if you enable notes on iCloud.

There is a problem to access to a note, especially when you have hundreds or thousands of notes. It is really hard to find out an interested note.

I developed an app: TapToCount-3W. This is a convenient and creative tool to write notes anywhere when you have an iPhone. By categories you define, it is very easy to organize your taps or notes. With a finger tapping on screen, you can create a tap with 3 pieces information: When, Where and What. "What" is a note associated to a tap.

Normally, I don't like to write a lot of text in my app's note. It is much better to use Notes.app or EverNote to write a note. Then, a question comes to my mind. Can I have a URL link in a note, and then I copy/paste the link to my app.

Yes, it is possible. Just follow these simple steps:

1. Click or tap a note's Add People icon
2. Enter an email, it can be just you!
3. Then a link is available in Sharing. I could not find Copy Link in iPhone, but it is in Mac.

In this way, I can have a link in my app.





From this story, I think that any shared resources in Apple devices should have a link or URL available for accessing.

References

• Stack Exchange - Ask Difference(Answers for your Apple questions): How to connection note with links in Notes.app?
• iOS app: TapToCount-3W

Connect to Wifi with QR Code

When you go to a new place, such as friends house, hotel, restaurant, airport, public place. One thing you want to find out is if there is Wifi network available? For free Wifi, it is quite easy to make connection. If a password is requite, you have to get it and enter it with your fingers, not so easy when password is long and complicated.

Recently, I read a news about NFC tag to access to Wifi. It is quite easy. You can move your phone to  a nearby NFC tag to access to Wifi. This intrigues me to a related tech: QR code. Soon I find out it is possible. Here are my findings.

Create Wifi QR Code

The first step is to create a Wifi QR Code. The most convenient way is to go to the web site qifi.org. You need to provide following information to generate a Wifi QR code:


where, SSID is a Wifi name, Key is a password, and the choice of Encryption is normally WPA/WPA2. With those information entered, you can generate Wifi QR code by clicking on "Generate!"



In addition to this web service, there are many free apps available on mobile phones. I tried some and some claimed to provide Wifi QR code. However, all my tests were failed. Another thing is that most of apps actually requite Internet access. Maybe they get QR code from online QR services in background. That makes sense. Otherwise, those app would include considerable QR library, which takes some extra space.

From my exploration, I find out the above web service is the most notable and reliable.

Scan QR Code

With Wifi QR code ready, you can use it as a way to easy access to Wifi network. You can save the Wifi QR code image to your mobile phone, or print it out and hanging out on your refrigerator. You can also leave it on your computer/mobile's web browser for people to scan.

Here is a tip. When you cut the QR code, add a title on the top of the image. This makes it easy to recall what this QR code is. There are many other usages of QR codes.



For iPhone users, it is very easy to access to Wifi network just by pointing Apple's Camera app at the code. In photo mode, there is a popup message on the top when you focus on the image:



Tap on the message, another popup window with options is displayed.



Note: your iPhone should be iOS 11 or above. If not showing this popup message, check your Setttings-Camera:



There are many QR Reader apps on iPhone, some claiming support for Wifi code. However, I tried many of them, none of their generated Wifi QR codes is working. Therefore, I choose qifi.org as my best choice.

Another interesting thing about iPhone is that you cannot use any third party apps to access to Wifi automatically by scanning QR code(I'll explain it later). All the QR code reader apps can read Wifi QR code and display its content as text. The following is an example:



If you cannot access to Wifi network automatically, you can still use QR reader app to get all the information, copy the password, and manually set your Wifi access.

For Android users, QR reader apps are requited. Based on the recommendation of qifi.org, two apps are listed in the following section of References.

Security Concerns

Although Wifi QR code techology provides a convenient and quick way to access Wifi network, it also introduce security vulnerability. This is my understanding. A Wifi QR code contains all the information about access to Wifi network. If an app could read all those information and request change of Wifi network without user content(in background, for example), it could change user's network environment without user notice. This would open security hole for hackers to steal user's mobile information, to install evil apps or to monitor user activities.

In this regard, iPhone is doing better. None of any none-Apple apps can do Wifi change automatically. Even for Apple's Camera app, it still displays a message to let user aware what's happening.

Another interesting thing I found is to memorize Wifi settings. I use iPhone. If I manually set up my home Wifi access, for example, my iPhone would remember my home Wifi settings. Next time when I come home, it would atomically reconnect me back to my home Wifi.

However, if I use Wifi QR code to access to home Wifi network, my iPhone will not remember those settings. The next time I am back to my home, my iPhone would not reconnect me back. I have to retype my password again for my home Wifi access.

This may be good for some people if they do not want to let users' iPhone to remember Wifi settings.

If you want your iPhone to remember those settings and want to use Wifi QR code, I found a secret. In the above qifi.org web page, there is an option "Hidden". Check this box and generate QR code. This will make your iPhone to remember Wifi settings!

References

• Wifi QR code online: qifi.org
• Android Wifi QR read app: Barcode Scanner from ZXing
• Android Wifi QR read app: NeoReader
• iOS QR app: QR Reader by TapMia
• All Questions for QR, the original inventor: QRcode.com

Kernel Panic

System panic or Kernel panic is a special issue in Mac. When it occurs, a screen curtain rolls down quickly like a transparent film blocking the whole screen. After the curtain is down, you cannot interact with Mac OS any more. There is no way you can save anything you have done. Therefore, it is extremely frustrating during the time you have lots of work done but not saved. Fortunately, most of time you can get back to normal OS after power down and up again.

I had this issue several times in my previous iMac 27 with Snow Leopard. Recently the kernel panic came back twice again in the past month. I remembered that I called Apple support line about this issue. I think that we spent about more than half hour to figure out any issue. Eventually, I was told that I had to reinstall my OS. After the re-installation of OS, the issue seems gone for a while. That's what I can remember about the issue.

The following screen actually is the one I had long time ago. There was no way to take screen shot, so I had to use my iPhone to take a picture. Today I saw this familiar one again. I decided to to re-intall my Lion OS.

Reinstall Mac OS Steps

Power off my Mac and restart it. When the power is up, hold command+R key till the screen is back.

Select Reinstall Mac OS. This time is for Lion:

Not sure if it did download Mac OS again to not, but it only take about 24 minute time:

Then, the Mac restarted. The next screen is to install Mac OS. This process took about 35 minutes.

When the reinstallation is finished, my Mac is back. All the programs and documents are still as same as before. I hope this reinstallation will keep the kernel panic away.

Reference

• Wikipeida: Kernel panic

iPad Interface Quirk: Parallel Fingers in Frame with Scrollbars

I tried to use iPad to read my programming blog long time ago and I realized that some frames with scrollbars were static, for example, CodeDom and Expression Calculator (2). I thought that iPad browser does not support scrollbars.

To my surprise, I just found a solution. In iPad, scroll bar are not visible by default. Actually, iPad does support scrollbars. In the case of frame, you have to move the content by two fingers. According to this blog(iPad interface quirk: scrolling frames lack scrollbars), it notes that this feature is in iPad's menu. I gave it a try. It does work.


In above case, it obviously shows the content flow. You can apply the same rule when you see a frame with content overflow even without scrollbar hint. The following picture is from another blog on this trick(Make Your iPad Dance with Two Fingers):