This is a benchmarking tool for testing iOS tile loading from our (or other) servers. It runs on both iPad and iPhone as a universal app.
On capable devices, choose to either use retina-compatible tiles drawn at actual 256px size or non-compatible tiles drawn at 512px in order to retain legibility.
These are our testbed options for concurrency approaches. For now, choose our regular method or two experimental asynchronous modes. More to come.
- Asynchronous prefetch takes a given (synchronous) tile request and before serving it, fires off several asynchronous network fetches of surrounding tiles straight to cache, if not already present. See Prefetch Radius and Max Concurrency options below.
- Asynchronous redraw takes a given (synchronous) tile request, fires off an asynchronous network fetch, along with a completion callback to refresh the entire map render redraw (since this can't be done on a per-tile basis), then returns an empty tile. When the network fetch completes, the tile is saved to cache, the redraw is requested, and one of two things happens. If a needed tile is in the cache, it is then drawn to screen. If not, another fetch is made for it, by which time the tile may now exist in cache (due to previous requests) or it will get queued up. This also relies on the mostly-unrelated Missing Tiles Depth option in standard Alpstein to give more of an illusion of tile loading speed.
If using the experimental modes, configure them here. Note that certain combinations can currently deadlock the application.
Consider a tile request for tile
X. Entering a radius value of
2 will synchronously request tile
X as well as kick off concurrent, asynchronous fetches for the following tiles (
2 tiles in all directions). These tiles go straight to local cache if successful, to be drawn later by subsequent tile requests (cache is always checked first before network fetching).
o o o o o o o o o o o o X o o o o o o o o o o o o
Aside from the normal synchronous tile fetches, how many simultaneous background fetches should be allowed.
Combined with asynchronous tile fetches & screen redraws, this option makes use of tiles already cached from up to
x lower-numbered zoom levels and draws them in the current zoom level while more accurate fetching is taking place. For example, if zoom level 12 is rendering and this option is set to 3, zoom levels 11, 10, and then 9 will be checked for appropriate tiles, which will be cut accordingly and rendered into place temporarily for zoom 12 until native tiles are available. This creates an illusion of faster loading while work is being done.
Configure the standard "show user" & "center on user" options here.
Draw borders on fetched tiles as well as their
Enter an alternate TileJSON URL to load or choose the default MapBox Streets.
Temporarily hide SDK functionality to see how Apple's MapKit shows the current view.
Introduce an artificial delay in tile loads to simulate various network conditions.