What is the Qibla line?
It is a straight line following the shortest distance to the Kaaba. Technically it is called the greatcircle. On maps it most often appears curved.3 Qibla Direction readings
The Qibla angle is displayed as degrees from North (Ipad bottom small map, Iphone top right).The green Qibla line will keep pointing towards Kaaba when the compass is activated (see below).
Compare Qibla direction to nearby houses and roads using satellite images.
Activate the compass
Compass button 'not active' and 'active':

Activating the compass will always activate the device location.
How should I use the 3 readings?
The displayed Qibla angle can be used for reference, but if you do know true North and have an accurate compass, please use it.The activated compass will keep rotating the map and with it the green Qibla line. Electrical/magnetic interference can however effect the result. Check if the map keeps pointing in the same directions when you move around.
The always accurate direction is the green qibla line displayed on the map/satellite picture! So if possible always compare this line to roads and houses in your neighbourhood. For example, the line could be pointing at the frontdoor of your neighbours house, or could be parallel to your road.
The Qibla line is always accurate. For proof, find any mosque on the map, double tap on it, a new qibla line will appear exactly parallel to the mosque. (ancient mosques might not be properly alligned)
Extra on Ipad
On your Ipad a small map will display the entire Qibla line. Tap on this map to see the entry point at the Kaaba.