Controlling Multithreading in Objective C

Question

I am a newbie in iPhone App development and I have a problem with thread controlling.

I have set two threads:

• first one updates a LABEL (LABEL1) after a specified time interval [it works fine]

• another does the same [updates another LABEL(LABEL2)] and is (controlled) started & stopped with a button press event:

  • 1st button-press starts the thread & makes the LABEL2 visible
  • 2nd press stops its execution & makes the corresponding LABEL2 invisible... and this way be controlled..

Button has a TUCHUPINSIDE event, and I am working with iPhone simulator.

It is working fine when the button is pressed normally (slowly), but when double-clicked or continuously clicked on the button and its execution state comes- then the corresponding LABEL2 is being updated faster then its interval.

Why is this happening?

Answer 1

Firstly, don't update any UI on any thread other than the Main Thread, you will have unpredicted results.

Why are you doing this on another thread? Are you just experimenting?

Also, I wouldn't advise using NSThread (neither do Apple). There are many more higher level concurrency API's you can use in objective-C, such as NSOperations, GCD....