Swift Combine Handling Multiple Publishers, Level Up Your Career as an iOS Developer!
When developing, it is rare to use only one publisher. Sometimes you will handle a single event from more than one publisher. Today’s tutorial will cover the functions
combineLatest, merge(with), and zip, which are used when using more than one publisher.
combineLatest subscribes to an additional publisher. Before you look, you need to remember that “when you receive an ouput from both publishers, closures get called”.
The code is simple. Multiply the integers in pub1 and pub2 to get the result.
Sent 2 to pub1. But nothing happens. Why?
combineLatest calls the closure “when it receives an ouput from both publishers”.
Since it received a value from pub1, but no value from pub2, the closure cannot be executed.
Merge literally means merge. It’s just a role that really merges them into one stream. This is useful when you want to treat two publishers as one publisher. Unlike combineLastest, when you receive one output from one publisher, it gets called.
As I told you, unlike combineLastest, one event triggers closure.
A zip combines elements from different publishers and provides element pairs as tuples.
Because zip “combines” values from each publisher, ike
combineLastest, if neither publisher has a value, it will not emit a value. And the bundled publishers are the “oldest-used” events from each publisher.
zip returns tuple value and it never gets called unless it receives values from each publisher. Because it makes it a couple,
combineLatest, when you have multiple publishers that rely on each other.
mergewhen you need to use more than one publishers as a single publisher.
zipwhen you need