Pro Android with Kotlin

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CHAPTER 8: APIs
As an input, you need the ID key from the Raw Contacts table; any function argument not 
null gets updated. For example, you can write the following inside the activity:
val rawId = ...
val cwr = ContactsWriter(this, contentResolver)
cwr.updateContact(rawId, null, null,
"[e-mail]", null)
cwr.doAll()
As a last function, we add the possibility to delete a contact, again based on the ID.
fun delete(id:String) {
var op = ContentProviderOperation.newDelete(
ContactsContract.RawContacts.CONTENT_URI)
.withSelection(ContactsContract.RawContacts.
CONTACT_ID + " = ?",
arrayOf(id))
opList.add(op.build())
}
Using it is similar to an update.
val rawId = ...
val cwr = ContactsWriter(this, contentResolver)
cwr.delete(rawId)
cwr.doAll()
Using Contacts System Activities
To read or update a single contact, you can avoid having to write your own user interface. 
Just use the system activity to access a contact. An appropriate intent call for creating a 
single contact looks like this:
val intent = Intent(Intents.Insert.ACTION)
intent.setType(ContactsContract.RawContacts.CONTENT_TYPE)
intent.putExtra(Intents.Insert.EMAIL, emailAddress)
.putExtra(Intents.Insert.EMAIL_TYPE,
CommonDataKinds.Email.TYPE_WORK)
.putExtra(Intents.Insert.PHONE, phoneNumber)
.PutExtra(Intents.Insert.PHONE_TYPE, Phone.
TYPE_WORK)
startActivity(intent)
This will open the contacts screen for creating a new contact and prefill the given fields.
To instead edit an existing contact, once you have the lookup key and the raw contact ID, as 
shown earlier, write the following:
val uri = Contacts.getLookupUri(id, lookupKey)
val intent = Intent(Intent.ACTION_EDIT)
// the following must be done in _one_ call, do not
// chain .setData() and .setType(), because they
// overwrite each other!

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