How to use the igniteui-angular.IgxToastPosition.Middle function in igniteui-angular

public ngOnInit(): void {
        this.localData = SINGERS;
        this.toast.position = IgxToastPosition.Middle;
    }

public ngOnInit() {
        this.products = DATA.map(e => {
            if (!e.UnitPrice) {
                e.UnitPrice = 1;
            }
            e.Ordered = Math.floor(Math.random() * e.UnitsInStock);
            return e;
        });
        this.toast.position = IgxToastPosition.Middle;
    }

public showToast(toast, position) {
        switch (position) {
            case "middle":
                this.toastPosition = IgxToastPosition.Middle;
                break;
            case "top":
                this.toastPosition = IgxToastPosition.Top;
                break;
            default:
                this.toastPosition = IgxToastPosition.Bottom;
        }

        toast.show();
    }
}

{
            email: "donnaprice@gmail.com",
            id: "859-496-2817",
            name: "Donna Price",
            photo: "assets/images/women/50.jpg"
        }
    ];

    public tagList = [
        { id: "All Users", text: "All Users" },
        { id: "My Team", text: "My Team" },
        { id: "USA Team", text: "USA Team" },
        { id: "Engineering Services", text: "Engineering Services" }
    ];

    public toastPosition: IgxToastPosition = IgxToastPosition.Middle;

    @ViewChild("chipsAreaCc", { read: IgxChipsAreaComponent, static: true })
    public chipsAreaCc: IgxChipsAreaComponent;

    @ViewChild("ccGroup", { read: IgxInputDirective, static: true })
    public ccGroup: IgxInputDirective;

    @ViewChild("textArea", { read: ElementRef, static: true })
    public textArea: ElementRef;

    @ViewChild("chipsArea", { read: IgxChipsAreaComponent, static: true })
    public chipsArea: IgxChipsAreaComponent;

    @ViewChild("inputForm", { read: IgxInputDirective, static: true })
    public inputBox: IgxInputDirective;

public transferData(source: IgxTreeGridComponent, target: IgxTreeGridComponent,
                        notification: IgxToastComponent) {
        target.shouldGenerate = true;
        target.clearCellSelection();
        this.targetData = source.getSelectedData();
        notification.message = `Transfered ${this.targetData.length} rows`;
        notification.position = IgxToastPosition.Middle;
        notification.displayTime = 1000;
        notification.show();
    }

public dataLoading(evt) {
        if (this.prevRequest) {
            this.prevRequest.unsubscribe();
        }
        this.loadingToast.message = "Loading Remote Data...";
        this.loadingToast.position = IgxToastPosition.Middle;
        this.loadingToast.autoHide = false;
        this.loadingToast.show();
        this.cdr.detectChanges();
        this.prevRequest = this.remoteService.getData(
            this.remoteCombo.virtualizationState,
            null,
            (data) => {
              this.remoteCombo.totalItemCount = data["@odata.count"];
              this.loadingToast.hide();
              this.cdr.detectChanges();
        });
    }

public dataLoading(evt) {
        if (this.prevRequest) {
            this.prevRequest.unsubscribe();
        }
        this.loadingToast.message = "Loading Remote Data...";
        this.loadingToast.position = IgxToastPosition.Middle;
        this.loadingToast.autoHide = false;
        this.loadingToast.show();
        this.cdr.detectChanges();
        this.prevRequest = this.remoteService.getData(
            evt,
            null,
            (data) => {
                this.remoteForDir.totalItemCount = data["@odata.count"];
                this.loadingToast.hide();
                this.cdr.detectChanges();
            });
    }

public transferData(source: IgxGridComponent, target: IgxGridComponent,
                        notification: IgxToastComponent) {
        target.shouldGenerate = true;
        target.clearCellSelection();
        this.targetData = source.getSelectedData();
        notification.message = `Transfered ${this.targetData.length} rows`;
        notification.position = IgxToastPosition.Middle;
        notification.displayTime = 1000;
        notification.show();
    }

public dataLoading(evt) {
        if (this.prevRequest) {
            this.prevRequest.unsubscribe();
        }
        this.loadingToast.message = "Loading Remote Data...";
        this.loadingToast.position = IgxToastPosition.Middle;
        this.loadingToast.autoHide = false;
        this.loadingToast.show();
        this.cdr.detectChanges();
        this.prevRequest = this.remoteService.getData(this.combo2.virtualizationState, this.combo2.searchValue, () => {
            this.combo2.triggerCheck();
            this.loadingToast.hide();
            this.cdr.detectChanges();
        });
    }