我的应用程序中有一个显示UIMapView的模态视图。然后，我将大量注释（超过800个）添加到此地图视图（下面的代码）。
问题是当所有引脚加载时，用户被迫等待一分钟左右。一旦所有800个引脚都在地图上，应用程序就会变得迟钝。
有人可以建议我如何改进我的代码吗？
谢谢。
#import "MapView.h"
#import "MapPlaceObject.h"
@implementation MapView
@synthesize mapViewLink, mapLocations, detail, failedLoad;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
-(void)addPins
{
for (MapPlaceObject * info in mapLocations) {
double latitude = info.longitude;
double longitude = info.latitude;
NSString * name = info.name;
NSString * addressline = info.addressOne;
NSString * postcode = info.postCode;
NSString * addresscomma = [addressline stringByAppendingString:@", "];
NSString * address = [addresscomma stringByAppendingString:postcode];
CLLocationCoordinate2D coordinate;
coordinate.latitude = latitude;
coordinate.longitude = longitude;
MyLocation *annotation = [[[MyLocation alloc] initWithName:name address:address coordinate:coordinate] autorelease];
[mapViewLink addAnnotation:annotation];
}
}
- (void)showLinks : (id)sender {
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
detail = [[DetailViewController alloc] initWithNibName:@"DetailViewController-iPad" bundle:nil];
}
else if (!detail) {
NSLog(@"Detail is None");
detail = [[DetailViewController alloc] initWithNibName:@"DetailViewController" bundle:nil];
}
int uniqueID = ((UIButton *)sender).tag;
//PlaceObject *info = [mapLocations objectAtIndex:uniqueID];
detail.UniqueID = uniqueID;
detail.hidesBottomBarWhenPushed = YES;
[self.navigationController pushViewController:detail animated:YES];
self.detail = nil;
[detail release];
}
- (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>) annotation{
if (annotation == mapView.userLocation){
return nil; //default to blue dot
}
MKPinAnnotationView *annView=[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"currentloc"];
annView.pinColor = MKPinAnnotationColorRed;
nameSaved = annotation.title;
for (PlaceObject * info in mapLocations) {
if (info.name == nameSaved) {
saveID = info.UniqueID;
}
}
UIButton *advertButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
advertButton.frame = CGRectMake(0, 0, 23, 23);
advertButton.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
advertButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
[advertButton addTarget:self action:@selector(showLinks:) forControlEvents:UIControlEventTouchUpInside];
advertButton.tag = saveID;
annView.rightCalloutAccessoryView = advertButton;
annView.animatesDrop=TRUE;
annView.canShowCallout = YES;
annView.calloutOffset = CGPointMake(-5, 5);
return annView;
}
- (void)dealloc
{
[mapViewLink release];
[mapLocations release];
[detail release];
self.failedLoad = nil;
[failedLoad release];
[super dealloc];
}
- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)viewWillAppear:(BOOL)animated {
if (firstTime) {
CLLocationCoordinate2D zoomLocation;
zoomLocation.latitude = 51.50801;
zoomLocation.longitude = -0.12789;
MKCoordinateRegion viewRegion = MKCoordinateRegionMakeWithDistance(zoomLocation, 15*METERS_PER_MILE, 15*METERS_PER_MILE);
MKCoordinateRegion adjustedRegion = [mapViewLink regionThatFits:viewRegion];
[mapViewLink setRegion:adjustedRegion animated:YES];
firstTime = NO;
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
firstTime = YES;
failedLoad = [[NSMutableArray alloc]init];
self.mapLocations = [BluePlaqueDatabase database].mapInfo;
[self addPins];
}
- (void)viewDidUnload
{
[mapViewLink release];
mapViewLink = nil;
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
答案 0 :(得分：10)
您可以在这里进行两项最大的速度提升：
UniqueID的设置方式。为了设置它，代码当前在每次创建注释视图时循环遍历所有注释（这可能在地图视图被缩放或滚动时发生 - 而不仅仅是初始时间。）首先，不是在UniqueID方法中搜索viewForAnnotation并使用按钮标记传递注释标识符，而是将UniqueID作为属性添加到自定义注释中类 MyLocation并在addPins中添加注释本身时设置属性：
annotation.uniqueID = info.UniqueID; // <-- give id to annotation itself
[mapViewLink addAnnotation:annotation];
您还可以将uniqueID作为参数添加到initWithName方法，而不是单独分配属性。
接下来，要实现注释视图重用，viewForAnnotation方法应如下所示：
- (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>) annotation{
if (annotation == mapView.userLocation){
return nil; //default to blue dot
}
NSString *reuseId = @"StandardPin";
MKPinAnnotationView *annView = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:reuseId];
if (annView == nil)
{
annView = [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:reuseId] autorelease];
annView.pinColor = MKPinAnnotationColorRed;
annView.animatesDrop = YES;
annView.canShowCallout = YES;
annView.calloutOffset = CGPointMake(-5, 5);
UIButton *advertButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
advertButton.frame = CGRectMake(0, 0, 23, 23);
advertButton.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
advertButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
annView.rightCalloutAccessoryView = advertButton;
}
else
{
//update the annotation property if view is being re-used...
annView.annotation = annotation;
}
return annView;
}
最后，要响应按下按钮并确定要显示详细信息的UniqueID，请实施calloutAccessoryControlTapped委托方法：
- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view
calloutAccessoryControlTapped:(UIControl *)control
{
MyLocation *myLoc = (MyLocation *)view.annotation;
int uniqueID = myLoc.uniqueID;
NSLog(@"calloutAccessoryControlTapped, uid = %d", uniqueID);
//create, init, and show the detail view controller here...
}
在所有这些更改之后，只有注释的初始加载将占用大部分时间。如果这仍然是一个问题，一种解决方案是仅添加在当前显示的区域中可见的注释，并在用户更改可见区域时添加/删除注释。
答案 1 :(得分：4)
我完全赞同安娜。但考虑到800 AnnotationViews同时会导致极端滞后的界面。因此，如果您的地图应提供滚动或缩放等用户交互，则最好实现注释视图的某种聚类。