How to rotate a UIImageView – ios sdk roulette tutorial

Animating an object using the ios sdk is very simple, but it's very difficult to retrieve an howto on the internet. So here you are a simple example

In this simple tutorial I'm going show to you how run a roulette, first of all we need the roulette, we will use the following image:

Now open Xcode and create a new project, you can choose "Single View Application" as your template.

Drag the image into the project.

Select the storyboard and insert a UIImageView and a Round Rect Button.

Open the ViewController.h header file and modify it, it should look like the following:

 1 //
 2 //  ViewController.h
 3 //  gigione
 4 //
 5 //  Created by Luigi D'Andrea on 10/05/12.
 6 //  Copyright (c) 2012 xAppSoftware.com. All rights reserved.
 7 //
 8 
 9 #import <UIKit/UIKit.h>
10 
11 @interface ViewController : UIViewController
12 {
13     IBOutlet UIImageView *theImageView;
14     IBOutlet UIButton    *theButton;
15     NSTimer              *theTimer;
16     float        angle;
17     BOOL         runStop;
18 }
19 
20 
21 @property (atomic, retain) IBOutlet UIImageView *theImageView;
22 @property (atomic, retain) IBOutlet UIButton    *theButton;
23 
24 -(IBAction)runRoulette:(id)sender;
25 
26 @end
27 

Open the ViewController.m file and just after insert the following code:

 1 @synthesize theButton, theImageView;
 2 
 3 -(void)rotateRoulette
 4 {
 5     self.theImageView.center=CGPointMake(self.theImageView.center.x, self.theImageView.center.y);
 6     self.theImageView.transform=CGAffineTransformMakeRotation (angle);
 7     angle+=0.4;
 8 }
 9 
10 
11 -(IBAction)runRoulette:(id)sender
12 {
13     if(!runStop)
14     {
15         theTimer = [NSTimer scheduledTimerWithTimeInterval:1.0/60.0 target:self selector:@selector(rotateRoulette) userInfo:nil repeats:YES];
16     }
17     else
18     {
19         [theTimer invalidate];
20         theTimer = nil;
21     }
22     runStop = !runStop;
23 }

Into the viewDidLoad method, before the   [super viewDidLoad]; statement add the following two lines to initialize the roulette values
    angle = 0;
    runStop = FALSE;

Now go to the storyboard,  right click on the "View Controller" and drag on the button, in the popop menu that will appear select theButton; right t click on the "View Controller" and drag on the UIImageView  in the popop menu that will appear select theImageView; right click on the button and drag on the "View Controller", in the popup menu that will appear select "runRoulette:".

That's all, now run your project, and try to tap on the button you should see the roulette rotating and stopping.

Gg1