我有一个应用程序，它在MapView中显示大约100个注释（带有自定义图钉图像，标注附件和注释图像）。在构建注释时，我存储了注释和构建之间的链接，因此我可以分配正确的构建并在之后打开正确的segue。
在iOS 6中，它们构建得非常快，我还在添加它们的同时启用了动画，因此一个引脚在另一个引脚之后被丢弃，但是在iOS7中使用苹果地图这是不可能的（？）。现在，在我的iPhone 4S上构建这100个注释需要1秒钟，这太长了。反正有没有改进代码？
- (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;
}
以下函数使用nspredicate获取当前注释的索引，以使用字典过滤数组。这样做的好处是，我可以在calloutAccessoryControlTapped时使用它：
-(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;
}
使用iPhone 4S后，最后一个引脚在视图加载后1.14秒内构建。
如果我手动搜索注释链接数组而不是像这样使用nspredicate函数：
//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];
日志表示最后一个引脚是在viewDidLoad之后1.89秒构建的。
如果我在viewDidApper而不是viewDidLoad中创建注释，View会立即显示，但背景需要一些时间才能加载，所以直到引脚掉落一切都是灰色的，这也不是很好......
答案 0 :(得分：1)
谢谢安娜的建议！我实现了这样的改进：
<强> 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;
}
标注：
- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control
{
Annotation *buildingAnnotation = (Annotation *)view.annotation;
selectedbuilding = buildingAnnotation.ID;
[self performSegueWithIdentifier:@"DetailViewController" sender:self];
}
还需要一些时间来显示所有注释。有没有机会进一步改进代码？
答案 1 :(得分：0)
我更新了关于Anna的回复和PhotosByLocation Sample Application的vievForAnnotation功能。它现在有效，我希望它是实现重用的正确方法......
- (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;
}