Introduction to UIActivity Indicator View

Why we are using UIActivity Indicator View ??

Displays an element that provides user feedback on the progress of a task or process with an unknown duration (to show the progress of a task with known duration, use UIProgressView instead). As long as the task or process continues, the activity indicator spins. A user does not interact with an activity indicator.

                                             Output of example code show in below image

                                                  

Programmatically create a UIActivity Indicator View

#import "ViewController.h"

@interface ViewController ()

{

    UIActivityIndicatorView *activityIndicator;

}

@end

@implementation ViewController

- (void)viewDidLoad

{

    [super viewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

    activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

    activityIndicator.alpha = 1.0;

    activityIndicator.center = CGPointMake(160, 360);

    activityIndicator.hidesWhenStopped = NO;

    

    [activityIndicator startAnimating];

    

    [self.view addSubview:activityIndicator];

    [self performSelector:@selector(stopActivity)withObject:nil afterDelay:5];

// This Activity indicator will stop after 5 seconds 

}

-(void)stopActivity

{

    [activityIndicator removeFromSuperview];

}








Below contents are from Apple Docs

Overview

Use an activity indicator to show that a task is in progress. An activity indicator appears as a “gear” that is either spinning or stopped.

You control when an activity indicator animates by calling the startAnimating and stopAnimating methods. To automatically hide the activity indicator when animation stops, set the hidesWhenStopped property to YES.
Starting in iOS 5.0, you can set the color of the activity indicator by using the color property.

Tasks

Initializing an Activity Indicator

• – initWithActivityIndicatorStyle:

Managing an Activity Indicator

• – startAnimating
• – stopAnimating
• – isAnimating
•    hidesWhenStopped  property

Configuring the Activity Indicator Appearance

•    activityIndicatorViewStyle  property
•    color  property

Properties

activityIndicatorViewStyle

The basic appearance of the activity indicator.

@property UIActivityIndicatorViewStyle activityIndicatorViewStyle

Discussion

See UIActivityIndicatorStyle for the available styles. The default value is UIActivityIndicatorViewStyleWhite.

Availability

• Available in iOS 2.0 and later.

Related Sample Code

• BonjourWeb

Declared In

UIActivityIndicatorView.h

color

The color of the activity indicator.

@property (readwrite, nonatomic, retain) UIColor *color

Discussion

If you set a color for an activity indicator, it overrides the color provided by the activityIndicatorViewStyle property.

Availability

• Available in iOS 5.0 and later.

Declared In

UIActivityIndicatorView.h

hidesWhenStopped

A Boolean value that controls whether the receiver is hidden when the animation is stopped.

@property BOOL hidesWhenStopped

Discussion

If the value of this property is YES (the default), the receiver sets its hidden property (UIView) to YES when receiver is not animating. If the hidesWhenStopped property is NO, the receiver is not hidden when animation stops. You stop an animating progress indicator with the stopAnimating method.

Availability

• Available in iOS 2.0 and later.

Declared In

UIActivityIndicatorView.h

Instance Methods

initWithActivityIndicatorStyle:

Initializes and returns an activity-indicator object.

- (id)initWithActivityIndicatorStyle:(UIActivityIndicatorViewStyle)style

Parameters

style

A constant that specifies the style of the object to be created. See UIActivityIndicatorStyle for descriptions of the style constants.

Return Value

An initialized UIActivityIndicatorView object or nil if the object couldn’t be created.

Discussion

UIActivityIndicatorView sizes the returned instance according to the specified style. You can set and retrieve the style of a activity indicator through the activityIndicatorViewStyle property.

Availability

• Available in iOS 2.0 and later.

Related Sample Code

• GeocoderDemo
• ListAdder
• LocateMe
• ThreadedCoreData
• UICatalog

Declared In

UIActivityIndicatorView.h

isAnimating

Returns whether the receiver is animating.

- (BOOL)isAnimating

Return Value

YES if the receiver is animating, otherwise NO.

Availability

• Available in iOS 2.0 and later.

See Also

• – startAnimating
• – stopAnimating

Related Sample Code

• LocateMe

Declared In

UIActivityIndicatorView.h

startAnimating

Starts the animation of the progress indicator.

- (void)startAnimating

Discussion

When the progress indicator is animated, the gear spins to indicate indeterminate progress. The indicator is animated until stopAnimating is called.

Availability

• Available in iOS 2.0 and later.

Related Sample Code

• BonjourWeb
• CryptoExercise
• GeocoderDemo
• ListAdder
• LocateMe

Declared In

UIActivityIndicatorView.h

stopAnimating

Stops the animation of the progress indicator.

- (void)stopAnimating

Discussion

Call this method to stop the animation of the progress indicator started with a call to startAnimating. When animating is stopped, the indicator is hidden, unless hidesWhenStopped is NO.

Availability

• Available in iOS 2.0 and later.

Related Sample Code

• CryptoExercise
• GeocoderDemo
• LocateMe

Declared In

UIActivityIndicatorView.h

Constants

UIActivityIndicatorStyle

The visual style of the progress indicator.

typedef enum {
   UIActivityIndicatorViewStyleWhiteLarge,
   UIActivityIndicatorViewStyleWhite,
   UIActivityIndicatorViewStyleGray,
} UIActivityIndicatorViewStyle;

Constants

UIActivityIndicatorViewStyleWhiteLarge

The large white style of indicator.
Available in iOS 2.0 and later.
Declared in UIActivityIndicatorView.h.

UIActivityIndicatorViewStyleWhite

The standard white style of indicator (the default).
Available in iOS 2.0 and later.
Declared in UIActivityIndicatorView.h.

UIActivityIndicatorViewStyleGray

The standard gray style of indicator.
Available in iOS 2.0 and later.
Declared in UIActivityIndicatorView.h.

Discussion

You set the value of the activityIndicatorViewStyle property with these constants.

Availability

• Available in iOS 2.0 and later.

Declared In

UIActivityIndicatorView.h