All software development requires discipline. Attention to detail, adhering to important conventions, and the willingness to do things the right way are necessary traits for any software developer worthy of the title. But if you are writing code that will be run on a modern desktop, laptop, or server you don’t need to worry too much about writing frugal code. Not only are those computing beasts, but they’re usually plugged into a power outlet.
That all changes when you are writing code that will run on a battery-powered device with (relatively speaking) significantly less horsepower. Your code should follow Einstein’s famous advice of only doing what needs to be done; nothing more, nothing less. Every line of code that runs will suck some juice out of the battery. Every object created brings your app that much closer to using up the available memory, putting your process at risk of being killed by the operating system.
Some developers new to, or unfamiliar with, iOS development consider Objective-C to be some dinosaur language that Apple hasn’t bothered replacing with something more “modern” such as Java or C#. They are wrong. Objective-C, which is C with some object-oriented syntax accompanied by a lightweight runtime, does not burden the device with a garbage collector, JIT compiler, etc. Those luxuries can be great for desktop and server programming, but are overkill for mobile devices.
In the mobile world, Responsiveness is king and the Battery is his queen. Every line of code you write should aim to satisfy those two masters. Write frugal code. Your users will appreciate it.