how to bind yes or no in single checkbox angular code example

Example 1: data binding on checkbox angular

<input #saveUserNameCheckBox
    id="saveUserNameCheckBox" 
    type="checkbox" 
    [checked]="saveUsername" 
    (change)="onSaveUsernameChanged(saveUserNameCheckBox.checked)" />

//component.ts
public saveUsername:boolean;

public onSaveUsernameChanged(value:boolean){
    this.saveUsername = value;
}

Example 2: ng-true-value

<input type="checkbox"
       ng-model="string"
       [name="string"]
       [ng-true-value="expression"]
       [ng-false-value="expression"]
       [ng-change="string"]>