Since iOS 4.0, I am aware freeing unnecessary object when the application is in inactive state so that the app can free up as much memory as possible. So in one of me location based app, I try to free the location service object when it is inactive:


- (void)applicationWillResignActive:(UIApplication *)application {
self.locationService = nil;
....
/*

If you are PC user, you will feel frustrating that you cannot charge your iPad through the PC's USB. I've thought that it is the hardware limitation of PC, but I was wrong. After install this ASUS ai charger:

http://event.asus.com/mb/2010/ai_charger/

You can now charge your iPad using the USB port of your PC. The software even claim it will charge iPhone and Ipod Touch faster that I didn't test. The software is not limited to ASUS motherboard, I successfully installed and used on my Foxconn motherboard without any problem.

[Chinese only]

如果你有的是時間，可以參考以下列表。只要中途轉一轉車（即用八達通一出一入）便可以節省車資。

例如，如果尖沙咀去羅湖，原本八達通票價是 $34.8，但如果在粉嶺或上水先出閘再入閘，車資便是$11+$19.5=$30.5了，可以節省 $4.3！

* 以下資料以電腦計算，並不確保資料正確。

起點|終點|八達通|轉車處|兩程總車資
===================
中環|馬場|19.5|大圍|18.6
中環|馬場|19.5|沙田|18.6
中環|羅湖|40.8|火炭|35.7
中環|落馬洲|40.8|火炭|35.7

[Chinese only]

起點|終點|單程|八達通
=============
石硤尾|大埔墟|8.5|8.6
石硤尾|太和|8.5|8.6
樂富|大埔墟|8.5|8.6
樂富|太和|8.5|8.6

(Chinese only)

比起 iPhone，iPad 我大畫面真是很適合用來畫畫。但是用手指畫好像還是不大舒適，不如大家DIY一枝 iPad 和 iPhone 也可以用的 stylus 吧! 材料只需要:

1. 3M 清潔海綿。
2. 一枝筆桿。選擇筆桿是最難的，我認為有幾個要素:
- 筆桿最好是金屬的，其實 iPhone stylus 的原理是把身體的電容經過筆桿再經3M 海綿傳到 touch screen，如果筆桿不是金屬，你便要在筆桿繞上金屬線和手接觸。
- 筆頭的孔最少要有5MM，或可以改裝到5MM，以給海綿通過。
- 筆頭最好是膠的，因為海綿之後就是筆頭，如果是金屬的碰到 touch screen 便不太好。
3. 一條電線。

這是我買的海綿，注意一定要3M的，其他的不保證可以。3M 藍色和粉紅色的海綿也可以。我買有百潔布的是因為它比較平。

If you are a writer and want to sell your book on iBookStore that people can read on iPad and upcoming iPhone with OS 4.0, check this out:

http://itunes.com/sellyourbooks

that Apple guide you how to sell books on iBookStore. Basically you will need the ISDN of your book and your book in ePub format.

[Chinese only]

等了兩個星期的 Camera Connection Kit 终於送到了，感謝好朋友幫手從美國記過來，因為聽說香港已經炒到六百多元了...

細到不能再細的包裝。

You can input emoji on your iPad without any secret tricks or both non-jailbroken or jailbroken iPad. Here is the instruction:

Below the code to use UITapGestureRecognizer to handle single tap and double tap. The code is designed that it won't fire single tap event if we got double tap event. The trick is use requireGestureRecognizerToFail to ask the single tap gesture wait for double tap event failed before it fire. So when the user tap on the screen, the single tap gesture recognizer will not fire the event until the double tap gesture recognizer. If the double tap gesture recognizer recognize the event, it will fire a double tab event and skip the single tap event, otherwise it will fire a single tap event.

Just got the 3G iPad for my friend. So I try to see if it works with Hong Kong carrier but cutting normal Mini SIM card to micro SIM. The contact point of my SIM card is different from the AT&T micro SIM card that is a little bit larger. To cut it, I just follow the size of the micro SIM of the AT&T card. The size is to tight that I need to cut the cut such that three sides of the contact points reaches the edge of the card.