Adding a ActivityIndicator to UIView - iphone

Question

I need to add an activityIndicator to a UIView.I have a button,when that button is clicked then it has to start animating. Actually when the button is clicked some data is received from rest service and parsing is done and then it is filled in UITableView.But the activity indicator is not getting animating..
- (void)viewDidLoad
{
[super viewDidLoad];
UIActivityIndicatorView *activityIndicator = [[UIActivityIndicatorView alloc]
initWithFrame:CGRectMake(0.0f, 0.0f, 20.0f, 20.0f)];
[activityIndicator setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleGray];
[self.view addSubview:activityIndicator];
}
-(IBAction)switchtoGetProviders
{
[activityIndicator startAnimating];
NSURL *urlString= [NSString stringWithFormat:#"http://230.32.232.32/services/service.svc/Xml"];
NSMutableURLRequest *request=[[[NSMutableURLRequest alloc] init]autorelease];
..............//calling data from service url
}
After reciving the whole data it is assigned to UITableView.
How can I get it working ?

Answer 1

You can't start and stop activity indicator in one single function/method.
There are two methods to do this things.
If the request is Asynchronous then you need to start activity indicator at button click and stop when you receive response.
But if the request is synchronous then it is not possible to start and stop activity in one function.for this you need to start animation on button click and make separate method for send synchronous request and call that method using [self performSelector:] method. At the end you need to stop animating.
Updates:
-(IBAction)switchtoGetProviders
{
[activityIndicator startAnimating];
[self performSelector:#selector(startRequest) withObject:nil afterDelay:0];
}
- (void)startRequest
{
NSURL *urlString= [NSString stringWithFormat:#"http://230.32.232.32/services/service.svc/Xml"];
NSMutableURLRequest *request=[[[NSMutableURLRequest alloc] init]autorelease];
..............//calling data from service url
[activityIndicator stopAnimating];
}

Answer 2

Probably this is due to the fact that you are making the webservice call and updating the UI at the same time on MAIN Thread. You must use GCD or detach another thread for making the webservice call.
Use this to detach a new thread
[NSThread detachNewThreadSelector:#selector(callWebserviceMethod:) toTarget:self withObject:nil];
In your code
-(IBAction)switchtoGetProviders
{
[activityIndicator startAnimating];
[NSThread detachNewThreadSelector:#selector(callWebserviceMethod:) toTarget:self withObject:nil];
}
-(void)callWebserviceMethod
{
NSURL *urlString= [NSString stringWithFormat:#"http://230.32.232.32/services/service.svc/Xml"];
NSMutableURLRequest *request=[[[NSMutableURLRequest alloc] init]autorelease];
}

Answer 3

You should define activityIndicator as a property, in your code you have it as a local variable.
After defining it as a property, change the assignment line to:
self.activityIndicator = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 20.0f, 20.0f)];

Answer 4

you need to get data from web service in background thread, as calling it on the main thread causes the UI to hang
see this

Answer 5

You have declared the UIActivityIndicatorView *activityIndicator in viewDidLoad method so it is local object only visible to this function you need to declare it in the header file or in class category in .m. When you declare the activityIndicator instance in the .h then you will be able to access this within your class. Either you can make it as property or just declare in .h then initialize in your viewDidLoad method without redeclaration.

Answer 6

just add this line in .h file
UIActivityIndicatorView *spinningWheel;
and in viewWillAppear method add this code..
spinningWheel = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(120, 200, 25.0, 25.0)];
spinningWheel.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;///UIActivityIndicatorViewStyleGray also use this if background white
[self.view addSubview:spinningWheel];
-(IBAction)switchtoGetProviders
{
[spinningWheel startAnimating];
NSURL *urlString= [NSString stringWithFormat:#"http://230.32.232.32/services/service.svc/Xml"];
NSMutableURLRequest *request=[[[NSMutableURLRequest alloc] init]autorelease];
..............//calling data from service url
}
and when you get data or response at that time stopAnimating like bellow..
[spinningWheel stopAnimating];

Answer 7

Just do one this , declare it in .h file mean declare glibly
.h
#interface yourViewController : UIViewController
{
IBOutlet UIActivityIndicatorView *activityIndicator;
}
.m
- (void)viewDidLoad
{
[super viewDidLoad];
activityIndicator = [[UIActivityIndicatorView alloc]initWithFrame:CGRectMake(143, 220, 37, 37)];
activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;
activityIndicator.color = [UIColor blackColor];
[self.view addSubview:activityIndicator];
}
-(IBAction)switchtoGetProviders
{
[activityIndicator startAnimating];
NSURL *urlString= [NSString stringWithFormat:#"http://230.32.232.32/services/service.svc/Xml"];
NSMutableURLRequest *request=[[[NSMutableURLRequest alloc] init]autorelease];
..............//calling data from service url
}