如何使用* ngIf切換類angular2

Question

您好我需要使用angular2 *ngIf語句來切換類

<i *ngIf="visible" [(ngClass)]="{{arrow}}"></i> <<這行代碼無法正常工作

---

這是我的ts代碼

private visible = true;
private i = 0;
private arrow = 'ic-v';
private showList(){
    if(this.i == 0){
        this.i = 1;
        this.visible = false;
        this.arrow = 'ic-v-up';
    }
    else
    {
        this.i = 0;
        this.visible = true;
        this.arrow = 'ic-v';
    }
}

Answer 1

ngClass是指令，將其用作[ngClass]作為屬性綁定指令。

[ngClass]="arrow"

或者更好

[ngClass]="{ 'ic-v': visible, 'ic-v-up': !visible }"

演示Plunker