MindMeister lets you connect individual topics in your mind maps with arrows, which you can also label. Here's how to add connections to your mind maps using the mobile apps:

On iOS (iPhone):

1) Select the topic you want to connect. A short tap is enough to open the black context menu.

2) Choose Connect from the context menu.

3) On the outside of the topic, a small green arrow icon will appear. Tap on that icon and drag it with your finger to the topic you want to connect with the first one. Let go once you've reached that topic.

If you want, you can now modify the shape of the arrow, and add a label to it: 

4) To add a label to the connection arrow, tap on the white round base of the arrow and select Edit Label in the black context menu. A bubble will appear in the middle of the arrow, and you'll be able to add your label there. 

5) To change the shape of the arrow, tap on the white, round base of the arrow. Two white and gray modifiers will appear, which you can move around to change the shape of the arrow. When you're done, just tap anywhere else on the map so the modifiers disappear again. 

On Android:

1) Long-tap on the topic you want to connect until the black context menu appears. Tap on the arrow on the right until you see the Connect option. Tap on it.

2) Tap on your target topic. A green connection arrow will appear between the two topics.

If you want, you can now modify the shape of the arrow, change its color, and add a label to it: 

3) To change the arrow's color, tap on the first topic again, which forms the arrow's origin. A white round button will appear in the center of the arrow. Tap on it, and then select Color from the black context menu. You can then select another color for the arrow.

4) Tap on the white button in the center of the arrow again to add/edit a label. The option will be provided in the black context menu.

5) To modify the shape of the arrow, tap on one of the two big white and gray modifiers and move them around until your arrow has the desired shape. Tap anywhere on the map to make the modifiers disappear again.