Question

In my app, I have noticed that it will run slowly for the first few seconds of running because objects are still being initialized, drawn to the screen, etc. How do I load these objects and create a bar to show the progress of the loading?

Answer 1

You can show a loading screen.
You can use different threads and detach threads.
Alternatively you can use a UIActivityIndicatorView or UIProgressBar to show that currently loading is on.

UIActivityIndicatorView basically is like when you start up your mac. A spinning circle.
UIProgressBar is a empty bar that fills up with blue as the loading increases.

A UIProgressBar has a variable called progress while you just send startAnimating and stopAnimating messages to a UIActivityIndicator

To read more about these two, check the links below:

Progress Bar Apple Documentation

Progress Bar Image

Activity Indicator Apple Documentation

Activity Indicator GIF Image

UPDATE TO YOUR QUESTION ON OTHER ANSWER:

What are you loading for? Does the class/object you are loading for have a delegate method? If you are saying

still being initialized and drawn to the screen

Considering object below is one of your objects
You could say

if (object) {
// saying just 'object' asks if it is non-zero/valid
}

Also to check if DRAWN to the screen try:

    if([self.view.subviews containsObject:object]) 

or

if([object superview] == self.view)

or the method

-(BOOL)isDescendantOfView:(UIView *)view;

Return Value YES if the receiver is an immediate or distant subview of view or if view is the receiver itself; otherwise NO.

ALSO: when i say self.view, it doesn’t have to be self, since loading view might be a different view. You could make an object to that other class and call that class instead of self. Like: if([otherClass.object superview] == otherClass.view)

You could also make an update method in the other class so you could say:

if([otherClass finishedLoading])

and then have this as the update method:

- (BOOL)finishedLoading {
return ([object superview] == self.view)
}

This is a lot to take in! Any other questions?