Convert UIViewController code to UIView

Question

I have an application which is based on animations. After hours of trying and searching the most effective animation processor (which would have low delay and the best memory management) I found out the amazing PNGAnimator (http://www.modejong.com/iPhone/). Funny thing is that I am actually using JPEGs (due to size), but that is not the problem.

The problem is that the class itself is a subclass of UIViewController and when I add it to my rootViewController the new view controller overlaps it - so all the interface elements (buttons...) are hidden under it.

That is why I would like to somehow convert the code to be a subclass of UIView. (So I can add the buttons over it) I tried converting the code myself, however the application would crash on an animation call. Could you please tell me what should I change in the code to so it will act as an UIView?

For example, I tried to change it in .h file to UIView and then in .m file, changing the references self.view to just self. Then in my root view controller adding it as an subview, but that does not show up and crashes either.

Here is the .h file:

//
//  ImageAnimatorViewController.h
//  PNGAnimatorDemo
//
//  Created by Moses DeJong on 2/5/09.
//

#import <UIKit/UIKit.h>

#define ImageAnimator15FPS (1.0/15)
#define ImageAnimator12FPS (1.0/12)
#define ImageAnimator25FPS (1.0/24)
#define ImageAnimator18FPS (1.0/18)

#define ImageAnimatorDidStartNotification @"ImageAnimatorDidStartNotification"
#define ImageAnimatorDidStopNotification @"ImageAnimatorDidStopNotification"

@class AVAudioPlayer;

@interface ImageAnimatorViewController : UIViewController {

@public

    NSArray *animationURLs;

    NSTimeInterval animationFrameDuration;

    NSInteger animationNumFrames;

    NSInteger animationRepeatCount;

    UIImageOrientation animationOrientation;

    NSURL *animationAudioURL;

    AVAudioPlayer *avAudioPlayer;

@private

    UIImageView *imageView;

    NSArray *animationData;

    NSTimer *animationTimer;

    NSInteger animationStep;

    NSTimeInterval animationDuration;

    NSTimeInterval lastReportedTime;
}

// public properties

@property (nonatomic, copy) NSArray *animationURLs;
@property (nonatomic, assign) NSTimeInterval animationFrameDuration;
@property (nonatomic, readonly) NSInteger animationNumFrames;
@property (nonatomic, assign) NSInteger animationRepeatCount;
@property (nonatomic, assign) UIImageOrientation animationOrientation;
@property (nonatomic, retain) NSURL *animationAudioURL;
@property (nonatomic, retain) AVAudioPlayer *avAudioPlayer;
@property (nonatomic, assign) CGRect viewCGRect;

// private properties

@property (nonatomic, retain) UIImageView *imageView;
@property (nonatomic, copy) NSArray *animationData;
@property (nonatomic, retain) NSTimer *animationTimer;
@property (nonatomic, assign) NSInteger animationStep;
@property (nonatomic, assign) NSTimeInterval animationDuration;

+ (ImageAnimatorViewController*) imageAnimatorViewController;

- (void) startAnimating;
- (void) stopAnimating;
- (BOOL) isAnimating;

- (void) animationShowFrame: (NSInteger) frame;

+ (NSArray*) arrayWithNumberedNames:(NSString*)filenamePrefix
                         rangeStart:(NSInteger)rangeStart
                           rangeEnd:(NSInteger)rangeEnd
                       suffixFormat:(NSString*)suffixFormat;

+ (NSArray*) arrayWithResourcePrefixedURLs:(NSArray*)inNumberedNames;

@end

And here the .m file:

//
//  ImageAnimatorViewController.m
//  PNGAnimatorDemo
//
//  Created by Moses DeJong on 2/5/09.
//

#import "ImageAnimatorViewController.h"

#import <QuartzCore/QuartzCore.h>

#import <AVFoundation/AVAudioPlayer.h>

@implementation ImageAnimatorViewController

@synthesize animationURLs, animationFrameDuration, animationNumFrames, animationRepeatCount,
imageView, animationData, animationTimer, animationStep, animationDuration, animationOrientation, viewCGRect;
@synthesize animationAudioURL, avAudioPlayer;

- (void)dealloc {
    // This object can't be deallocated while animating, this could
    // only happen if user code incorrectly dropped the last ref.

    NSAssert([self isAnimating] == FALSE, @"dealloc while still animating");

  self.animationURLs = nil;
  self.imageView = nil;
  self.animationData = nil;
  self.animationTimer = nil;

  [super dealloc];
}

+ (ImageAnimatorViewController*) imageAnimatorViewController
{
  return [[[ImageAnimatorViewController alloc] init] autorelease];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
  // Return YES for supported orientations
  return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

// Implement loadView to create a view hierarchy programmatically, without using a nib.

- (void)loadView {
    UIView *myView = [[UIView alloc] initWithFrame:viewCGRect];
    [myView autorelease];
    self.view = myView;
    /*UIView *myView = [[UIView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame];
    [myView autorelease];
    self.view = myView;

    // FIXME: Additional Supported Orientations

    if (animationOrientation == UIImageOrientationUp) {
        // No-op
    } else if (animationOrientation == UIImageOrientationLeft) {
        // 90 deg CCW
        //[self rotateToLandscape];
    } else if (animationOrientation == UIImageOrientationRight) {
        // 90 deg CW
        //[self rotateToLandscapeRight];
    } else {
        NSAssert(FALSE,@"Unsupported animationOrientation");
    }
*/
    // Foreground animation images

    UIImageView *myImageView = [[UIImageView alloc] initWithFrame:self.view.frame];
    [myImageView autorelease];
    self.imageView = myImageView;

    // Animation data should have already been loaded into memory as a result of
    // setting the animationURLs property

    NSAssert(animationURLs, @"animationURLs was not defined");
    NSAssert([animationURLs count] > 1, @"animationURLs must include at least 2 urls");
    NSAssert(animationFrameDuration, @"animationFrameDuration was not defined");

    // Load animationData by reading from animationURLs

    NSMutableDictionary *dataDict = [NSMutableDictionary dictionaryWithCapacity:[animationURLs count]];

    NSMutableArray *muArray = [NSMutableArray arrayWithCapacity:[animationURLs count]];
    for ( NSURL* aURL in animationURLs ) {
        NSString *urlKey = aURL.path;
        NSData *dataForKey = [dataDict objectForKey:urlKey];

        if (dataForKey == nil) {
            dataForKey = [NSData dataWithContentsOfURL:aURL];
            NSAssert(dataForKey, @"dataForKey");

            [dataDict setObject:dataForKey forKey:urlKey];
        }

        [muArray addObject:dataForKey];
    }
    self.animationData = [NSArray arrayWithArray:muArray];

    int numFrames = [animationURLs count];
    float duration = animationFrameDuration * numFrames;

    self->animationNumFrames = numFrames;
    self.animationDuration = duration;

    [self.view addSubview:imageView];

    // Display first frame of image animation

    self.animationStep = 0;

    [self animationShowFrame: animationStep];

    self.animationStep = animationStep + 1;

    if (animationAudioURL != nil) {
        AVAudioPlayer *avPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:animationAudioURL
                                                                         error:nil];
    [avPlayer autorelease];
        NSAssert(avPlayer, @"AVAudioPlayer could not be allocated");
        self.avAudioPlayer = avPlayer;

        [avAudioPlayer prepareToPlay];      
    }
}

// Create an array of file/resource names with the given filename prefix,
// the file names will have an integer appended in the range indicated
// by the rangeStart and rangeEnd arguments. The suffixFormat argument
// is a format string like "%02i.png", it must format an integer value
// into a string that is appended to the file/resource string.
//
// For example: [createNumberedNames:@"Image" rangeStart:1 rangeEnd:3 rangeFormat:@"%02i.png"]
//
// returns: {"Image01.png", "Image02.png", "Image03.png"}

+ (NSArray*) arrayWithNumberedNames:(NSString*)filenamePrefix
                              rangeStart:(NSInteger)rangeStart
                                rangeEnd:(NSInteger)rangeEnd
                             suffixFormat:(NSString*)suffixFormat
{
    NSMutableArray *numberedNames = [[NSMutableArray alloc] initWithCapacity:40];

    for (int i = rangeStart; i <= rangeEnd; i++) {
        NSString *suffix = [NSString stringWithFormat:suffixFormat, i];
        NSString *filename = [NSString stringWithFormat:@"%@%@", filenamePrefix, suffix];

        [numberedNames addObject:filename];
    }

    NSArray *newArray = [NSArray arrayWithArray:numberedNames];
    [numberedNames release];
    return newArray;
}

// Given an array of resource names (as returned by arrayWithNumberedNames)
// create a new array that contains these resource names prefixed as
// resource paths and wrapped in a NSURL object.

+ (NSArray*) arrayWithResourcePrefixedURLs:(NSArray*)inNumberedNames
{
    NSMutableArray *URLs = [[NSMutableArray alloc] initWithCapacity:[inNumberedNames count]];
    NSBundle* appBundle = [NSBundle mainBundle];

    for ( NSString* path in inNumberedNames ) {
        NSString* resPath = [appBundle pathForResource:path ofType:nil];    
        NSURL* aURL = [NSURL fileURLWithPath:resPath];

        [URLs addObject:aURL];
    }

    NSArray *newArray = [NSArray arrayWithArray:URLs];
    [URLs release];
    return newArray;
}


// Invoke this method to start the animation

- (void) startAnimating
{
    self.animationTimer = [NSTimer timerWithTimeInterval: animationFrameDuration
                                             target: self
                                           selector: @selector(animationTimerCallback:)
                                           userInfo: NULL
                                            repeats: TRUE];

    [[NSRunLoop currentRunLoop] addTimer: animationTimer forMode: NSDefaultRunLoopMode];

    animationStep = 0;

    if (avAudioPlayer != nil)
        [avAudioPlayer play];

    // Send notification to object(s) that regestered interest in a start action

    [[NSNotificationCenter defaultCenter]
     postNotificationName:ImageAnimatorDidStartNotification
     object:self];  
}

// Invoke this method to stop the animation, note that this method must not
// invoke other methods and it must cancel any pending callbacks since
// it could be invoked in a low-memory situation or when the object
// is being deallocated. Invoking this method will not generate a
// animation stopped notification, that callback is only invoked when
// the animation reaches the end normally.

- (void) stopAnimating
{
    if (![self isAnimating])
        return;

    [animationTimer invalidate];
    self.animationTimer = nil;

    animationStep = animationNumFrames - 1;
    [self animationShowFrame: animationStep];

    if (avAudioPlayer != nil) {
        [avAudioPlayer stop];
        avAudioPlayer.currentTime = 0.0;
        self->lastReportedTime = 0.0;
    }

    // Send notification to object(s) that regestered interest in a stop action

    [[NSNotificationCenter defaultCenter]
     postNotificationName:ImageAnimatorDidStopNotification
     object:self];  
}

- (BOOL) isAnimating
{
    return (animationTimer != nil);
}

// Invoked at framerate interval to implement the animation

- (void) animationTimerCallback: (NSTimer *)timer {
    if (![self isAnimating])
        return;

    NSTimeInterval currentTime;
    NSUInteger frameNow;

    if (avAudioPlayer == nil) {
        self.animationStep += 1;

//      currentTime = animationStep * animationFrameDuration;
        frameNow = animationStep;
    } else {
        currentTime = avAudioPlayer.currentTime;
        frameNow = (NSInteger) (currentTime / animationFrameDuration);
    }

    // Limit the range of frameNow to [0, SIZE-1]
    if (frameNow == 0) {
        frameNow = 0;
    } else if (frameNow >= animationNumFrames) {
        frameNow = animationNumFrames - 1;
    }

    [self animationShowFrame: frameNow];
//  animationStep = frameNow + 1;

    if (animationStep >= animationNumFrames) {
        [self stopAnimating];

        // Continue to loop animation until loop counter reaches 0

        if (animationRepeatCount > 0) {
            self.animationRepeatCount = animationRepeatCount - 1;
            [self startAnimating];
        }
    }
}

// Display the given animation frame, in the range [1 to N]
// where N is the largest frame number.

- (void) animationShowFrame: (NSInteger) frame {
    if ((frame >= animationNumFrames) || (frame < 0))
        return;

    NSData *data = [animationData objectAtIndex:frame];
    UIImage *img = [UIImage imageWithData:data];
    imageView.image = img;
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
  self.animationRepeatCount = 0;

    [self stopAnimating];
}

@end

Thank you very much for any advice!

Answer 1

Not sure why you got downvoted. I think your issue is that the UIViewController subclass has the loadView function implemented, and depends on it to build the UI. In the case of a view controller, this function is called automatically to build the view if it is not loaded from a .xib. You can try calling this functional manually after you create your object, and it should do pretty much the same thing.

Keep in mind that the shouldAutorotateToInterfaceOrientation function is also a UIViewController function and will never be called on a UIView