How to display a “spinning wheel” indicator in the centre of your screen

Sometimes you want to tell the user that something’s happening behind the scenes and that there’s no need to panic. While your process is happening you can display a “spinning gear” in the middle of your screen.

One way of doing this is via a UIActivityIndicatorView.

You can create them in Interface Builder, but it’s very easy to create one and show it if and when necessary. Here’s how:

- (UIActivityIndicatorView *)indicator {
    if (!_indicator) {
        _indicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    }
    return _indicator;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.indicator.center = self.view.center;
    [self.view addSubview:self.indicator];
}

This creates it in the centre of your UI, but it’s invisible until switched on like so:

// to start spinning
[self.indicator startAnimating];

// and to stop it again
[self.indicator stopAnimating];

The UIActivityIndicatorView has a property that automatically hides it when stopped, so all we have to worry about is starting and stopping it when necessary.

• https://developer.apple.com/library/IOs/documentation/UIKit/Reference/UIActivityIndicatorView_Class/Reference/UIActivityIndicatorView.html