Understanding UIActivity Indicator not Displaying

Introduction

The UIActivityIndicatorView is a powerful tool for creating an indeterminate animation in iOS, which can be used to show that an operation is in progress. However, it’s not uncommon to encounter issues with the indicator not displaying as expected.

In this article, we’ll delve into the world of UIActivityIndicatorView and explore common pitfalls that may prevent the indicator from appearing.

What is UIActivityIndicatorView?

The UIActivityIndicatorView is a view that displays an indeterminate animation, which can be used to indicate that an operation is in progress. It’s commonly used in situations where you need to show that your app is working on something in the background, such as loading data from a server or performing a long-running computation.

To use the UIActivityIndicatorView, you’ll need to create an instance of the class and add it to your view hierarchy using the addSubview: method. You can then start animating the indicator by calling the startAnimating method.

Common Issues with UIActivityIndicatorView

There are several common issues that may prevent the UIactivityIndicator from displaying as expected.

1. Not Setting a Frame

If you don’t set a frame for the activity indicator, it will default to the size of your view. This can make it difficult to position the indicator exactly where you want it.

// Bad practice
UIActivityIndicatorView *activity = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];

[self.view addSubview:activity];

2. Not Setting Autoresizing Mask

The activity indicator has a default autoresizing mask that allows it to change size based on its superview. This can make it difficult to position the indicator exactly where you want it.

// Bad practice
UIActivityIndicatorView *activity = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];

activity.autoresizingMask = UIViewAutoresizingFlexibleSize;
[self.view addSubview:activity];

3. Not Setting HidesWhenStopped

If you don’t set hidesWhenStopped to YES, the activity indicator will remain visible even when it’s stopped animating.

// Bad practice
UIActivityIndicatorView *activity = [[UIActivityIndicator style:UIActivityIndicatorViewStyleWhite] init];

[self.view addSubview:activity];

4. Not Setting a Frame for the Table View

If you don’t set a frame for your table view, it will default to the size of your view. This can make it difficult to position the activity indicator exactly where you want it.

// Bad practice
UITableView *tableView = [[UITableView alloc] init];

[self.view addSubview:tableView];

5. Not Setting a Non-White Background Color for the Table View

If you don’t set a non-white background color for your table view, it may be difficult to see the activity indicator.

// Good practice
UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"Cell"];

cell.backgroundColor = [UIColor blackColor];
[self.view addSubview:cell];

6. Using a White Activity Indicator

Using a white activity indicator can make it difficult to see, especially on light-colored backgrounds.

// Good practice
UIActivityIndicatorView *activity = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

[self.view addSubview:activity];

Best Practices for Using UIActivityIndicatorView

To ensure that your UIactivityIndicator is displaying correctly, follow these best practices:

• Set a frame for the activity indicator to position it exactly where you want it.
• Set an autoresizing mask to prevent the activity indicator from changing size based on its superview.
• Set hidesWhenStopped to NO until you’re sure that the activity indicator is visible.
• Use a non-white background color for your table view or other views that may obscure the activity indicator.
• Choose an activity indicator style that will be most visible against your app’s background colors.

Example Code

Here’s an example of how you might use UIactivityIndicator in a view controller:

#import <UIKit/UIKit.h>

@interface ActivityViewController : UIViewController

@property (nonatomic, strong) IBOutlet UITableView *tableView;

@end

@implementation ActivityViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Create the activity indicator
    UIActivityIndicatorView *activity = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];

    // Set a frame for the activity indicator
    activity.frame = CGRectMake(0, 50, 100, 100);

    // Set an autoresizing mask to prevent the activity indicator from changing size based on its superview
    activity.autoresizingMask = UIViewAutoresizingFlexibleSize;

    // Add the activity indicator as a subview of the table view
    [self.tableView addSubview:activity];

    // Start animating the activity indicator
    [activity startAnimating];

    // Set hidesWhenStopped to NO until you're sure that the activity indicator is visible
    activity.hidesWhenStopped = NO;
}

@end

By following these best practices and using UIactivityIndicator correctly, you can create a clear and informative user experience for your app’s users.

Last modified on 2023-10-16