如何添加注释的MKMapView asyncronously？ [英] How to add annotations to MKMapView asyncronously?

问题描述

我有很多的注释被添加到一个的MKMapView。当我添加注释，应用程序冻结的时间很短。我明白，主线程是不允许添加用户界面来查看，如果这是真的，怎么我做这个操作不会冻结应用程序的唯一主题？

  //在viewDidLoad中
对于（NSManagedObject *在requestResults对象）{
     CustomAnnotation * customAnnotation = [[CustomAnnotation的alloc]初始化];
     customAnnotation.title = object.title;
     customAnnotation.coordinate = CLLocationCoordinate2DMake（[object.latitude的doubleValue]，[object.longitude的doubleValue]）;
     [_mapView addAnnotation：customAnnotation];
}
} //结束viewDidLoad中 - （MKAnnotationView *）的MapView：（*的MKMapView）的MapView viewForAnnotation：（ID＆LT; MKAnnotation＆GT;）注释
{
//显示了具有自定义图像注释
    MKPinAnnotationView * customPinView = [[MKPinAnnotationView页头] initWithAnnotation：注释reuseIdentifier：@mapAnnotation];
    CustomAnnotation * customAnnotation =（ID）注释;
    customPinView.image = [UIImage的imageNamed：@绿色];
    返回customPinView;
}
 

解决方案

您可以使用<一个href=\"https://developer.apple.com/library/ios/#documentation/Performance/Reference/GCD_libdispatch_Ref/Reference/reference.html\"相对=nofollow>大中央调度 - GCD 这样做的。

试着用：

   - （无效）viewDidLoad中
{
  dispatch_async（dispatch_get_global_queue（0，0），^ {
     对于（NSManagedObject *在requestResults对象）
     {
        CustomAnnotation * customAnnotation = [[CustomAnnotation的alloc]初始化];
        customAnnotation.title = object.title;
        customAnnotation.coordinate = CLLocationCoordinate2DMake（[object.latitude的doubleValue]，[object.longitude的doubleValue]）;
        dispatch_async（dispatch_get_main_queue（），^ {
           [_mapView addAnnotation：customAnnotation];
        }）;
     }
  }）;
}
 

这是一个很好的教程：<一href=\"http://www.raywenderlich.com/4295/multithreading-and-grand-central-dispatch-on-ios-for-beginners-tutorial\"相对=nofollow> GCD和线程

I have alot of annotations to be added to a mkmapview. When i add the annotations, the app freezes for a short period of time. I have understand that the main thread is the only thread allowed to add UI to view, if this is true, how to i make this operation not freeze the app?

// in viewdidLoad
for (NSManagedObject *object in requestResults) {
     CustomAnnotation *customAnnotation = [[CustomAnnotation alloc] init];
     customAnnotation.title = object.title;
     customAnnotation.coordinate = CLLocationCoordinate2DMake([object.latitude doubleValue], [object.longitude doubleValue]);
     [_mapView addAnnotation:customAnnotation];
} 
} // end viewdidload

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
// shows the annotation with a custom image
    MKPinAnnotationView *customPinView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"mapAnnotation"];
    CustomAnnotation *customAnnotation = (id) annotation;
    customPinView.image = [UIImage imageNamed:@"green"];
    return customPinView;
}

解决方案

You can use Grand Central Dispatch - GCD for doing this.

Try with:

- (void)viewDidLoad
{
  dispatch_async(dispatch_get_global_queue(0, 0), ^{
     for (NSManagedObject *object in requestResults)
     {
        CustomAnnotation *customAnnotation = [[CustomAnnotation alloc] init];
        customAnnotation.title = object.title;
        customAnnotation.coordinate = CLLocationCoordinate2DMake([object.latitude doubleValue], [object.longitude doubleValue]);
        dispatch_async(dispatch_get_main_queue(), ^{
           [_mapView addAnnotation:customAnnotation];
        });
     }
  });
}

This is a nice tutorial: GCD and threading

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