swift - Are there performance differences for saveInBackground v saveEventually? -

is there reason use saveinbackground instead of saveeventually? both have callbacks available. there difference in performance or functionality? exact same function saveeventually having network check in it?

my understanding same because they're compared in docs docs don't explicitly state that. saveinbackground pushed higher priority thread saveeventually or thread same?

update:

as there performance differences mikeg notes below made simple fallback save method in case situations. employ everywhere run normal save operation. saveinbackground , fallback saveeventually:

func saveinbackgroundifnotsuccesssaveeventually(object: pfobject, completion: (() -> ())?) {  object.saveinbackgroundwithblock({ (success, error) -> void in      if !success {         object.saveeventually({ (success, error) -> void in              if success {                 completion?()             }              if error != nil {                 nslog(error!.localizeddescription)             }         })      } else if success {         completion?()     }      if error != nil {         nslog(error!.localizeddescription)     } }) 

}

the 2 functions different. saveinbackground performs save asynchronously. means calls save function, , returns calling thread functionality may continue without having wait save function complete , return. have been using saveinbackground in app , have literally done hundreds of tests , long internet connection available, function completed within 3 seconds max, within 1 second. how function behaves when no internet connection available unsure, if in situation in unsure if connection available, need make save, go saveeventually().

saveeventually on other hand perform save @ unspecified time in future. if internet connection unavailable, wait until connection available , perform save. believe, though not positive, function dispatched queue has quality of service background , not high priority task, can put off until resources available @ unspecified time in future. take anywhere seconds minutes hours suppose, if connection unavailable long.

edit: forgot answer question directly, "are there performance differences...". answer yes!