One of the guys I work with stumbled upon a quick and easy way to use logic to check if a value is not a valid number (non dependant on type). The logic is as follows:

"123" == +"123" // true

"asdf" == +"asdf" // false

Now you can check to see if your variables are numbers even when they come through as strings (eg. from a form)

I've been doing a lot of IOS on the weekends lately and today I ran into two problems in regard to String Format Specifiers. I found out that if I don't use them correctly then xcode gives me runtime errors that look like they are related to bad memory management, but it's just because I used the wrong specifier. I wrestled with this for a few hours, but someone was able to answer it quickly for me on Stack Overflow.