修复 theme-change 示例语法报错

pages/API/theme-change/theme-change.uvue

@@ -58,7 +58,7 @@
       },
       radioChange(e : UniRadioGroupChangeEvent) {
         const theme = e.detail.value
-        setAppTheme(theme)
+        this.setAppTheme(theme)
         uni.showToast({
           icon: 'none',
           title: '当前选中:'+theme,
@@ -84,8 +84,8 @@
           this.current = this.items.indexOf(this.appTheme)
         }
       })
-      this.osThemeChangeId = bindOsThemeChange()
-      this.appThemeChangeId = bindAppThemeChange()
+      this.osThemeChangeId = this.bindOsThemeChange()
+      this.appThemeChangeId = this.bindAppThemeChange()
     },
     onUnload() {
       //注销监听