向 iPhone MapView 添加多个注释很慢 [英] Adding multiple annotations to iPhone MapView is slow
本文介绍了向 iPhone MapView 添加多个注释很慢的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有一个代码,它需要一个位置的标题和地址,然后从谷歌地图 csv 获取坐标,然后添加注释.它可以工作,但是当我想一次添加 50 个或更多注释时,它会冻结大约 30-40 秒,然后显示注释,所以我想知道的是我是否搞砸了内存管理,这就是为什么它这么慢,或者什么的别的?我可以加快速度吗?
I have code that takes a title and an address of a location,then get coordinates from google maps csv, then add annotation. It works, but when I want to add 50 or more annotation at once it freezes for about 30-40 seconds and then displays annotations, so what I want to know is did I screw up memory management and that's why it's so slow, or something else? Can I speed it up?
代码如下:
- (void) addAnnotation: (NSString*) annoTitle: (NSString*) annoAddress
{
NSString *address = annoAddress;
NSString *urlString = [NSString stringWithFormat:@"http://maps.google.com/maps/geo?q=%@&output=csv", [address stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSString *locationString = [NSString stringWithContentsOfURL:[NSURL URLWithString:urlString]];
NSArray *listItems = [locationString componentsSeparatedByString:@","];
float langcoord = [[listItems objectAtIndex:2] floatValue];
float longcoord = [[listItems objectAtIndex:3] floatValue];
CLLocationCoordinate2D coord = CLLocationCoordinate2DMake(langcoord, longcoord);
// Create an instance of MapPoint with the current data
Annotation *annotation = [[Annotation alloc] initWithCoordinate:coord title:annoTitle];
// Add it to the map view
[mapView addAnnotation:annotation];
// MKMapView retains its annotations, so we can release it
[annotation release];
}
推荐答案
MapKit 上的多个 pin 使用以下方法.
Following methods are use for the multiple pin on MapKit.
-(void)viewWillAppear:(BOOL)animated {
NSArray *AS=[NSArray arrayWithArray:[reports objectAtIndex:0]];
for (int i=0; i<[AS count]; i++) {
Place* home = [[[Place alloc] init] autorelease];
home.name = [[AS objectAtIndex:i] valueForKey:@"comments"];
home.latitude = [[[AS objectAtIndex:i] valueForKey:@"latitude"]floatValue];
home.longitude = [[[AS objectAtIndex:i] valueForKey:@"longitude"]floatValue];
valueForKey:@"latitude"]floatValue],[[[AS objectAtIndex:i] valueForKey:@"longitude"]floatValue]];
PlaceMark* from = [[[PlaceMark alloc] initWithPlace:home] autorelease];
[mapView addAnnotation:from];
}
[self centerMap];
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}
两个引脚之间的集中映射
Centralized Map between two pins
-(void) centerMap
{
MKCoordinateRegion region;
CLLocationDegrees maxLat = -90;
CLLocationDegrees maxLon = -180;
CLLocationDegrees minLat = 120;
CLLocationDegrees minLon = 150;
NSArray *temp=[NSArray arrayWithArray:[NSArray arrayWithArray:[reports objectAtIndex:0]]];
for (int i=0; i<[temp count];i++) {
Place* home = [[[Place alloc] init] autorelease];
home.latitude = [[[temp objectAtIndex:i] valueForKey:@"latitude"]floatValue];
home.longitude =[[[temp objectAtIndex:i] valueForKey:@"longitude"]floatValue];
PlaceMark* from = [[[PlaceMark alloc] initWithPlace:home] autorelease];
CLLocation* currentLocation = (CLLocation*)from ;
if(currentLocation.coordinate.latitude > maxLat)
maxLat = currentLocation.coordinate.latitude;
if(currentLocation.coordinate.latitude < minLat)
minLat = currentLocation.coordinate.latitude;
if(currentLocation.coordinate.longitude > maxLon)
maxLon = currentLocation.coordinate.longitude;
if(currentLocation.coordinate.longitude < minLon)
minLon = currentLocation.coordinate.longitude;
region.center.latitude = (maxLat + minLat) / 2;
region.center.longitude = (maxLon + minLon) / 2;
region.span.latitudeDelta = maxLat - minLat;
region.span.longitudeDelta = maxLon - minLon;
}
[mapView setRegion:region animated:YES];
}
在此处定义多重注释.
- (MKAnnotationView *)mapView:(MKMapView *)map viewForAnnotation:(id <MKAnnotation>)annotation
{
if (annotation == mapView.userLocation)
return nil;
MKPinAnnotationView *pin = (MKPinAnnotationView *) [mapView dequeueReusableAnnotationViewWithIdentifier: @"asdf"];
if (pin == nil)
pin = [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier: @"asdf"] autorelease];
else
pin.annotation = annotation;
pin.userInteractionEnabled = YES;
UIButton *disclosureButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
[disclosureButton setFrame:CGRectMake(0, 0, 30, 30)];
pin.rightCalloutAccessoryView = disclosureButton;
pin.pinColor = MKPinAnnotationColorRed;
pin.animatesDrop = YES;
[pin setEnabled:YES];
[pin setCanShowCallout:YES];
return pin;
}
这篇关于向 iPhone MapView 添加多个注释很慢的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文