Trigger to enable users to change the Case Owner through a proxy field via a publisher action in Salesforce1

SetNewOwner.trigger

trigger SetNewOwner on Case (before insert, before update) {
    for (Case eachCase : Trigger.new) {
        if (eachCase.NewOwner__c != null) {
            eachCase.OwnerId = eachCase.NewOwner__c;
            eachCase.NewOwner__c = null;
        }
    }
}