Building MapView Annotations is very slow - ios

Question

I have an application which shows something around 100 Annotations (with custom pin-images, callout accessories and annotation-images) in a MapView. While building the annotations I store a link between annotation and building so I can assign the right building and open the right segue afterwards.
In iOS 6 they get built really fast, I also enabled animation while adding them, so one pin got dropped after the other, but with apple maps in iOS7 this isn't possible anymore (?). Now building those 100 annotations takes over 1 second on my iPhone 4S and that's too long. Is there anyway to improve the code?
- (void)viewDidLoad
...
//creating annotations
annotationlink = [[NSMutableArray alloc] init];
for (int i = 0; i < data.count; i++) {
NSDictionary *dataItem = [data objectAtIndex:i];
//storing annotation in array for link
Annotation *buildingannotation = [[Annotation alloc] init];
NSNumber *index = [NSNumber numberWithInteger:i];
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:index, indexKey, buildingannotation, annotationKey, nil];
[annotationlink addObject:dict];
buildingannotation.title = [dataItem objectForKey:#"Building"];
buildingannotation.subtitle = [dataItem objectForKey:#"Info"];
MKCoordinateRegion buildingcoordinates;
buildingcoordinates.center.latitude = [[dataItem objectForKey:#"Latitude"] floatValue];
buildingcoordinates.center.longitude = [[dataItem objectForKey:#"Longitude"] floatValue];
buildingannotation.coordinate = buildingcoordinates.center;
[self.mapView addAnnotation:buildingannotation];
}
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation
{
if ([annotation isKindOfClass:[MKUserLocation class]]){
return nil;
}
MKAnnotationView *pinView = (MKAnnotationView *)
[self.mapView dequeueReusableAnnotationViewWithIdentifier:pinIdentifier];
MKAnnotationView *customAnnotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:pinIdentifier];
customAnnotationView.canShowCallout = YES;
//right button to detail view
UIButton* disclosureButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
customAnnotationView.rightCalloutAccessoryView = disclosureButton;
//left button for image
NSInteger *buildingindex = [self getIndex:annotation];
NSDictionary *dataItem = [data objectAtIndex:buildingindex];
NSString* filename = [dataItem objectForKey:#"Thumb"];
filename = [filename stringByAppendingString:#"#2x.jpg"];
NSString* resourceimagePath = [resourcePath stringByAppendingPathComponent:filename];
Image = [UIImage imageWithContentsOfFile:resourceimagePath];
UIImageView *AnnotationThumb = [[UIImageView alloc] initWithImage:Image];
AnnotationThumb.frame = CGRectMake(0, 0, 31, 31);
customAnnotationView.leftCalloutAccessoryView = AnnotationThumb;
//annotation image
customAnnotationView.image = [UIImage imageNamed:#"Annotation_white.png"];
return customAnnotationView;
return pinView;
}
the following function gets the index of the current annotation using nspredicate to filter the array with the dictionaries. the advantage of this is the fact, that i can also use it when calloutAccessoryControlTapped:
-(NSInteger*) getIndex:(Annotation*)searchannotation
{
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"%K == %#", annotationKey, searchannotation];
NSArray *filteredarray = [annotationlink filteredArrayUsingPredicate:predicate];
NSDictionary *building = [filteredarray objectAtIndex:0];
NSInteger *buildingIndex = [[building objectForKey:indexKey] integerValue];
return buildingIndex;
}
With an iPhone 4S the last pin is built 1.14 seconds after the view gets loaded.
if i search the annotation link array manually instead of using nspredicate function like this:
//left button for image
int buildingIndex;
for (int i = 0; i < annotationlink.count; i++) {
NSDictionary *annotationDict = [annotationlink objectAtIndex:i];
if ([[annotationDict objectForKey:annotationKey] isEqual:annotation]) {
buildingIndex= [[annotationDict objectForKey:indexKey] integerValue];
i = annotationlink.count;
}
}
NSDictionary *dataItem = [data objectAtIndex:buildingIndex];
the log says that the last pin is built 1.89 seconds after the viewDidLoad.
if i create the annotations in viewDidApper instead of viewDidLoad the View is shown off course immediately but the background takes some time to load so until the pins are dropped everything is gray which is also not very nice...

Answer 1

Thank you Anna for your suggestions! I implemented the improvements like this:
Annotation.h:
#import <MapKit/MKAnnotation.h>
#interface Annotation : NSObject <MKAnnotation> {}
#property(nonatomic, assign) CLLocationCoordinate2D coordinate;
#property(nonatomic, copy) NSString *title;
#property(nonatomic, copy) NSString *subtitle;
#property NSInteger *ID;
#end
Annotation.m:
#import "Annotation.h"
#implementation Annotation
#synthesize coordinate, title, subtitle, ID;
#end
ViewDidAppear:
//creating annotations
for (int i = 0; i < data.count; i++) {
NSDictionary *dataItem = [data objectAtIndex:i];
Annotation *buildingannotation = [[Annotation alloc] init];
buildingannotation.ID = i;
buildingannotation.title = [dataItem objectForKey:#"Building"];
buildingannotation.subtitle = [dataItem objectForKey:#"Subtitle"];
MKCoordinateRegion buildingcoordinates;
buildingcoordinates.center.latitude = [[dataItem objectForKey:#"Latitude"] floatValue];
buildingcoordinates.center.longitude = [[dataItem objectForKey:#"Longitude"] floatValue];
buildingannotation.coordinate = buildingcoordinates.center;
[self.mapView addAnnotation:buildingannotation];
}
viewForAnnotation:
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation
{
if ([annotation isKindOfClass:[MKUserLocation class]]){
return nil;
}
MKAnnotationView *pinView = (MKAnnotationView *)
[self.mapView dequeueReusableAnnotationViewWithIdentifier:pinIdentifier];
if (pinView == nil) {
MKAnnotationView *customAnnotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:pinIdentifier];
customAnnotationView.canShowCallout = YES;
//right button to detail view
UIButton* disclosureButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
customAnnotationView.rightCalloutAccessoryView = disclosureButton;
//left button for image
Annotation *buildingAnnotation = (Annotation *)annotation;
NSInteger *buildingindex = buildingAnnotation.ID;
NSString *filePath = [thumbname objectAtIndex:buildingindex];
UIImageView *AnnotationThumb = [[UIImageView alloc] initWithImage:[UIImage imageWithContentsOfFile:filePath]];
AnnotationThumb.frame = CGRectMake(0, 0, 31, 31);
customAnnotationView.leftCalloutAccessoryView = AnnotationThumb;
//annotation image
customAnnotationView.image = [UIImage imageNamed:#"Annotation_white.png"];
return customAnnotationView;
} else {
pinView.annotation = annotation;
}
return pinView;
}
Callout:
- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control
{
Annotation *buildingAnnotation = (Annotation *)view.annotation;
selectedbuilding = buildingAnnotation.ID;
[self performSegueWithIdentifier:#"DetailViewController" sender:self];
}
Takes still some time for showing all Annotations. Is there any chance to further improve the code?

Answer 2

I updated the vievForAnnotation function regarding to Anna's reply and the PhotosByLocation Sample Application. It works now and I hope it's the correct way to implement the reuse...
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation
{
if ([annotation isKindOfClass:[MKUserLocation class]]){
return nil;
}
MKAnnotationView *buildingAnnotationView = (MKAnnotationView *) [mapView dequeueReusableAnnotationViewWithIdentifier:pinIdentifier];
if (buildingAnnotationView) {
[buildingAnnotationView prepareForReuse];
} else {
buildingAnnotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:pinIdentifier];
buildingAnnotationView.canShowCallout = YES;
//right button to detail view
UIButton* disclosureButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
buildingAnnotationView.rightCalloutAccessoryView = disclosureButton;
//annotation image
buildingAnnotationView.image = [UIImage imageNamed:#"Annotation_white.png"];
}
//left button for image
Annotation *buildingAnnotation = (Annotation *)annotation;
NSInteger *buildingindex = buildingAnnotation.ID;
NSString *filePath = [thumbname objectAtIndex:buildingindex];
UIImageView *AnnotationThumb = [[UIImageView alloc] initWithImage:[UIImage imageWithContentsOfFile:filePath]];
AnnotationThumb.frame = CGRectMake(0, 0, 31, 31);
buildingAnnotationView.leftCalloutAccessoryView = AnnotationThumb;
return buildingAnnotationView;
}