Set a breakpoint in dependent library in XCode 4.2

In order to set a breakpoint in a dependent library and break at the main project, you will need first set the breakpoint in the library and then change the scope of the breakpoint to user.
Launch the main project will hit the breakpoint you just set in the library project.

Iphone simulator folder in Lion with Xcode 4.2

By default, the library folder under user is hidden in Lion with Xcode 4.2, so you will not be able to access the iPhone simulator folder shown below.

/Users/(your user name)/Library/Application Support/iPhone Simulator

To show the library folder, run the following command from terminal window:

chflags nohidden ~/Library/

Note the library folder must be the one under your name, not the one under root.

Fresh installation of Lion on Mac without CD or USB stick

Lion has to be upgraded on Mac, however, you may want to have a fresh install of Lion to get rid of the old application or settings from the Snow Leopard. The following steps can be used to make a refresh Lion installation.
1. Upgrade Snow Leopard to Lion as Apple suggested from app store (paying for $29)
2. Reboot Mac while holding option key
3. Select the restore disk for starting
4. Select Disk Utility and erase the main hard disk drive. This may erase the old Snow Leopard.
5. Restore Lion, it will start a refresh Lion installation.

Cheers
Jonathan