BackendlessDataCollection

This is an implementation of the class than conforms to the iOS/macOS Collection protocol enabling to retrieve and iterate over a collection of objects stored in a Backendless data table.

Functions that returns data are mapped to various Backendless Data APIs.

The Iterator returned by the implementation lets you access either all objects from the data table or a subset determined by a where clause.

Whant the examples now

All retrieved objects are saved locally to enable faster access in future iterations.
The collection is not thread safe.

User Guide

Create collection

var people: BackendlessDataCollection?

1. people = BackendlessDataCollection(entityType: Person.self)

2. let queryBuilder = DataQueryBuilder()
   queryBuilder.setWhereClause(whereClause: "age > 20")
   people = BackendlessDataCollection(entityType: Person.self, queryBuilder: queryBuilder)

Description

BackendlessDataCollection(entityType: Person.self)

Create ordinary collection for table Person which reflects all records from it.

• the total size of objects (table rows) is retrieved on object creation;
• you can iterate through the entire collection;
• every iteration will perform calls to the Backendless server;
• the add, insert and remove operations do not perform calls to Backendless server;

BackendlessDataCollection(entityType: Person.self, queryBuilder: queryBuilder)

Create collection as a slice of data for table Person. Will reflect only a subset of data which satisfy argument whereClause (in or case it age > 20).
Main features are the same as in point (1).

• the total size of objects satisfied the whereClause is retrieved on object creation;
• you can iterate only through the subset of objects;
• the add, insert and remove operations do not perform calls to Backendless server;

Properties and special functions

count - returns the total number of the Backendless collection elements which reflect the row size in the underlying table.

isEmpty - never makes api call to Backendless. Returns true if Backendless collection is empty.

sort(by:) - sorts the collection in place, using the given predicate as the comparison between elements.

makeIterator() - returns an iterator over the elements of the collection

Handlers

The handlers below can be used to work with UI components - reloading tableView, showing activity indicator etc.

public typealias RequestStartedHandler = () -> Void
public typealias RequestCompletedHandler = () -> Void
public typealias BackendlessFaultHandler = (Fault) -> Void
public typealias BackendlessDataChangedHandler = (EventType) -> Void

public var requestStartedHandler: RequestStartedHandler? - indicates when the request to server starts.

public var requestCompletedHandler: RequestCompletedHandler? - indicates when the request to server is completed.

public var errorHandler: BackendlessFaultHandler? - handles errors that may occur during requests to Backendless.

Examples

for-in

for person in people {
    print((person as! Person).name ?? "")
}

for-in with premature break

for person in people {
    print((person as! Person).name ?? "")
    if (person as! Person).name == "Bob" {
        break
    }
}

for-each

people.forEach({ person in
    print((person as! Person).name ?? "")
})

iterator

let personIterator = people.makeIterator()
while let person = personIterator.next() as? Person {
    print("\(person.objectId ?? ""), \(person.name ?? "")")
}