RMTileCache Class Reference
| Inherits from | NSObject |
| Conforms to | RMTileCache |
| Declared in | RMTileCache.h |
Overview
An RMTileCache object manages memory-based and disk-based caches for map tiles that have been retrieved from the network.
An RMMapView has one RMTileCache across all tile sources, which is further divided according to each tile source’s uniqueTilecacheKey property in order to keep tiles separate in the cache.
An RMTileCache is a key component of offline map use. All tile requests pass through the tile cache and are served from cache if available, avoiding network operation. If tiles exist in cache already, a tile source that is instantiated when offline will still be able to serve tile imagery to the map renderer for areas that have been previously cached. This can occur either from normal map use, since all tiles are cached after being retrieved, or from proactive caching ahead of time using the beginBackgroundCacheForTileSource:southWest:northEast:minZoom:maxZoom: method.
Tasks
Initializing a Cache Manager
Identifying Cache Objects
Adding Caches to the Cache Manager
-
– addCache: -
tileCachesproperty
Background Downloading
Properties
backgroundCacheDelegate
A delegate to notify of background tile cache download operations.
@property (nonatomic, weak) id<RMTileCacheBackgroundDelegate> backgroundCacheDelegateDiscussion
A delegate to notify of background tile cache download operations.
Declared In
RMTileCache.hisBackgroundCaching
Whether or not the tile cache is currently background caching.
@property (nonatomic, readonly, assign) BOOL isBackgroundCachingDiscussion
Whether or not the tile cache is currently background caching.
Declared In
RMTileCache.htileCaches
The list of caches managed by a cache manager. This could include memory-based, disk-based, or other types of caches.
@property (nonatomic, readonly, strong) NSArray *tileCachesDiscussion
The list of caches managed by a cache manager. This could include memory-based, disk-based, or other types of caches.
Declared In
RMTileCache.hInstance Methods
addCache:
Adds a given cache to the cache management system.
- (void)addCache:(id<RMTileCache>)cacheParameters
- cache
A memory-based or disk-based cache.
Discussion
Adds a given cache to the cache management system.
Declared In
RMTileCache.hbeginBackgroundCacheForTileSource:southWest:northEast:minZoom:maxZoom:
Tells the tile cache to begin background caching. Progress during the caching operation can be observed by implementing the RMTileCacheBackgroundDelegate protocol.
- (void)beginBackgroundCacheForTileSource:(id<RMTileSource>)tileSource southWest:(CLLocationCoordinate2D)southWest northEast:(CLLocationCoordinate2D)northEast minZoom:(NSUInteger)minZoom maxZoom:(NSUInteger)maxZoomParameters
- tileSource
The tile source from which to retrieve tiles.
- southWest
The southwest corner of the geographic area to cache.
- northEast
The northeast corner of the geographic area to cache.
- minZoom
The minimum zoom level to cache.
- maxZoom
The maximum zoom level to cache.
Discussion
Tells the tile cache to begin background caching. Progress during the caching operation can be observed by implementing the RMTileCacheBackgroundDelegate protocol.
Declared In
RMTileCache.hcancelBackgroundCache
Cancel any background caching.
- (void)cancelBackgroundCacheDiscussion
Cancel any background caching.
This method returns immediately so as to not block the calling thread. If you wish to be notified of the actual cancellation completion, implement the tileCacheDidCancelBackgroundCache: delegate method.
Declared In
RMTileCache.hinitWithExpiryPeriod:
Initializes and returns a newly allocated cache object with specified expiry period.
- (id)initWithExpiryPeriod:(NSTimeInterval)periodParameters
- period
A period of time after which tiles should be expunged from the cache.
Return Value
An initialized cache object or nil if the object couldn’t be created.
Discussion
Initializes and returns a newly allocated cache object with specified expiry period.
If the init method is used to initialize a cache instead, a period of 0 is used. In that case, time-based expiration of tiles is not performed, but rather the cached tile count is used instead.
Declared In
RMTileCache.htileCountForSouthWest:northEast:minZoom:maxZoom:
A count of the number of tiles that would be downloaded in a background tile cache download operation.
- (NSUInteger)tileCountForSouthWest:(CLLocationCoordinate2D)southWest northEast:(CLLocationCoordinate2D)northEast minZoom:(NSUInteger)minZoom maxZoom:(NSUInteger)maxZoomParameters
- southWest
The southwest corner of the geographic area to cache.
- northEast
The northeast corner of the geographic area to cache.
- minZoom
The minimum zoom level to cache.
- maxZoom
The maximum zoom level to cache.
Return Value
The number of tiles representing the coverage area.
Discussion
A count of the number of tiles that would be downloaded in a background tile cache download operation.
Declared In
RMTileCache.h