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What is the Concat Operator in RxSwift?

Concat Operator

RxSwift: Concat Operator


  • Chains two or more Observable sequences.
  • Concatenates the output of multiple Observables into a single Observable in Observable order.
  • First Observable completes followed by the second and so forth.
  • If trying to concatenate a “hot” Observable, concat will not see it and will not emit.
  • Used as a static function or instance method of an Observable.
  • If the inner Observable emits an error, the result Observable emits error and terminates.
  • N.B: Observable sequences are strongly typed so you can only concatenate sequences where the elements are the same type.
  • If you want to add to the start of an Observable, use the .startWith(_:) operator.



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