IF条件变化后UI不刷新

@Entry 
@Component 
struct Page { 
 @State title: string = 'Hello' 
 showMessage: Boolean = false; 
  
 build() { 
   Row() { 
     Column() { 
       // showMessage 为常规变量，他的更新不应该引起if组件的重新渲染，显示Text组件'Hello World' 
       Text(this.title) 
         .fontSize(50) 
         .onClick(() => { 
           this.showMessage = true; 
           this.title = 'Show message' 
         }) 
       if (this.showMessage) { 
         Text('Hello World') 
           .fontSize(50) 
       } 
     } 
   } 
   .height('100%') 
 } 
}