TCCMapTileAnimation

An iOS library for creating an animated map overlay from tiled images.

Features

Create an animated overlay on an MKMapView by using map tiles from either the local file system or from a map tile server, where each frame of animation consists of a set of tiles.
Allow users to play, pause, and jump/scrub through the animation timeline.
Animates the overlay consistently and smoothly. Depending on the graphical power of the device, there should be little to no tiling or flickering when drawing a frame of the animation.
When the user pans around the map, the overlay falls back to retrieving and rendering tiles on demand.

TCCMapTileAnimation does not provide any UI playback controls, but please take a look at the demo project to see how to wire up UI controls to the overlay.

Getting Started

Installation

If you use CocoaPods, add pod 'TCCMapTileAnimation' to your Podfile, then run pod install.

You can also manually add the .m and .h files in the TCCMapTileAnimation directory to your project, or create a static library from those files and add the library to your project.

Prerequisites

TCCMapTileAnimation uses NSURLCache to quickly look up and render overlay tiles that have already been fetched from the network. This must be set up explicitly by your app, ideally in application:didFinishLaunchingWithOptions.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    NSURLCache *cache = [[NSURLCache alloc] initWithMemoryCapacity:4 * 1024 * 1024
                                                      diskCapacity:20 * 1024 * 1024
                                                          diskPath:nil];
    [NSURLCache setSharedURLCache:cache];
    
    ...
}

Creating the overlay

NSArray *templateURLs = @[@"http://url.to/first_frame/{z}/{x}/{y}", @"http://url.to/second_frame/{z}/{x}/{y}"];
self.overlay = [[TCCAnimationTileOverlay alloc] initWithMapView:self.mapView templateURLs:templateURLs frameDuration:0.50 minimumZ:3 maximumZ:9 tileSize:CGSizeMake(256, 256)];
self.overlay.delegate = self;
[self.mapView addOverlay:self.overlay];

Creating the overlay renderer

- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay
{
	if ([overlay isKindOfClass:[TCCAnimationTileOverlay class]]) {
        self.animatedTileRenderer = [[TCCAnimationTileOverlayRenderer alloc] initWithOverlay:overlay];
        // Optional - draws tile grid debug info
        // self.animatedTileRenderer.drawDebugInfo = YES;
        self.animatedTileRenderer.alpha = .75;
        return self.animatedTileRenderer;
	}
	return nil;
}

Fetching tiles and starting animation

[self.overlay fetchTilesForMapRect:self.mapView.visibleMapRect zoomLevel:self.animatedTileRenderer.renderedTileZoomLevel progressHandler:^(NSUInteger currentTimeIndex) {
    // Show loading progress
	[self.downloadProgressView setProgress:(CGFloat)currentTimeIndex / self.animatedTileOverlay.numberOfAnimationFrames animated:YES];
} completionHandler:^(BOOL success, NSError *error) {
	if (success) {
		[self.animatedTileOverlay startAnimating];
        return;
	}
}];

Rendering the animation

// When the overlay has started animating, it calls this delegate method when each frame of animation ticks.
// It is its responsibility to tell the overlay renderer to redraw for each frame.
- (void)animationTileOverlay:(TCCAnimationTileOverlay *)animationTileOverlay didAnimateWithAnimationFrameIndex:(NSInteger)animationFrameIndex
{
	[self.animatedTileRenderer setNeedsDisplayInMapRect:self.mapView.visibleMapRect];
	...    
}

Stopping animation

[self.overlay pauseAnimating];

Scrubbing between frames of animation

// This action is connected to the "Value Changed" event for the playback slider
- (IBAction)onSliderValueChange:(id)sender
{
    // Only advance the animated overlay to the next frame if the slider no longer matches the current frame index
	NSInteger sliderVal = floor(self.timeSlider.value);
    if (sliderVal == self.animatedTileOverlay.currentFrameIndex) return;
    [self.animatedTileOverlay moveToFrameIndex:frameIndex isContinuouslyMoving:YES];
}

// This action is connected to "Touch Up Inside" and "Touch Up Outside" for the playback slider
- (IBAction)finishedSliding:(id)sender
{
    NSInteger sliderVal = floor(self.timeSlider.value);
    [self.animatedTileOverlay moveToFrameIndex:frameIndex isContinuouslyMoving:NO];
}

Reacting to user input on the map

- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated
{
    // When the user moves/zooms/rotates the map, it should pause loading or animating, since
    // otherwise we might not have fetched the tile data necessary to display the overlay
    // for the new region.
    if (self.animatedTileOverlay.currentAnimationState == TCCAnimationStateAnimating ||
        self.animatedTileOverlay.currentAnimationState == TCCAnimationStateLoading) {
        [self.animatedTileOverlay pauseAnimating];
    }
}

Check out the demo project MapTileAnimationDemo to get a more in-depth look at incorporating TCCMapTileAnimation into a project.

Technical Details

It relies on cached HTTP network responses (from NSURLCache) to provide good performance during animation.

tww0003 / TCCMapTileAnimation