iOS 7 Programming Cookbook

22.2. Storing and Synchronizing Dictionaries in iCloud

Problem

You want to store key-value data in dictionary form in iCloud and seamlessly read and write to this centralized and synchronized dictionary from various devices and from various iCloud accounts.

Solution

Use the NSUbiquitousKeyValueStore class.

The data that you store in iCloud using the NSUbiquitousKeyValueStore is uniquely created in iCloud using the provision profile with which you sign the app and the end user’s iCloud account. In other word, you simply store values in iCloud using the NSUbiquitousKeyValueStore class, not worrying if one user’s data is going to clash with another user’s data. iCloud does that separation for you.

In Recipe 22.1, we used the Capabilities tab of our target settings to enable iCloud for our app. However, to use the NSUbiquitousKeyValueStore class, we need to enable the key-value store for iCloud as well. This can be done from the same Capabilities tab of your target settings. Once you are in the Capabilities tab, expand the iCloud section if it’s not already expanded, and then ensure that the Use key-value store option is ticked, as shown in Figure 22-5.

Discussion

The NSUbiquitousKeyValueStore class works very similar to the NSUserDefaults class. It can store string, Boolean, integer, float and other values. Each one of the values has to have a key associated with it. You will then be able to read the values by passing the keys to this class. The difference between the NSUbiquitousKeyValueStore ...