Swift CoreData Relationship

CoreData relationship The development process has many details that need attention. A little careless will be trapped somewhere unable to move.

1. Create an entity Contactsdetail (member) and Contactsgroup (group)
2. Contactsdetail adding a property and setting the property value type
3. Contactsgroup adding a property and setting the property value type
4. Contactsdetail add relationship, name. And destination is selected as detail for Contactsgroup,inverse. Delete rule is set to nullify (invalid)
5. Contactsgroup, add relationship. Name. And destination is selected as Contactsgroup for Contactsdetail,inverse. Delete rule is set to cascade (concatenation)
6. Generate the required files (. h. m) to complete the preparatory work

Start code

Call Method **********************************

Get all Groups

Controllistarray = Databaseclass.dbcontactsgroupreadalldata ()

Insert a group

Databaseclass.dbcontactsgroupinsert (["Name": input!])

Delete a group

Let group = controllistarray! [Indexpath.row] as Contactsgroup

Databaseclass.dbcontactsgroupdeleteobject (Group)

Gets all members of the specified group (to pass in the group entity object)

Controllistarray = Databaseclass.dbcontactsdetailreadalldata (currentgroup!)

Create a member in a specified group

Databaseclass.dbcontactsdetailinsert (group!, datadic: ["name": "Zhang San", "Sex": "Male", "Age": "18"])

Delete a member from a specified group

Let Detaildata = controllistarray! [Indexpath.row] as Contactsdetail

Databaseclass.dbcontactsdetaildeleteobject (Detaildata)

Details notes

1. When you create a relationship, selecting inverse may not have a value. To create and name all the relationships of two entities, you can then select each
2. Delete the group, but the members are not removed from the database. Delete rule for group relationships must select Cascade (that is, concatenation, delete in series).

Reference

Swift CoreData Relationship