iphone - NSMutableArray似乎过早发布

我正在尝试将注释添加到数组以在地图上放置多个图钉。我将所有内容都放在for循环中。第一次循环通过时，就可以将对象添加到数组中。当它返回时...数组中有0个对象。谁能告诉我为什么？

编辑：我正在使用ARC。

-(void)plotMultipleLocs {
float latitude;
float longitude;
NSRange commaIndex;
NSString *coordGroups;
for (int i=0; i<=cgIdArray.count; i++) {
    coordGroups = [cgInAreaArray objectAtIndex:i];
    commaIndex = [coordGroups rangeOfString:@","];
    latitude = [[coordGroups substringToIndex:commaIndex.location] floatValue];
    longitude = [[coordGroups substringFromIndex:commaIndex.location + 1] floatValue];
    CLLocationCoordinate2D loc = CLLocationCoordinate2DMake(latitude, longitude);
    MKCoordinateRegion reg = MKCoordinateRegionMakeWithDistance(loc, 1000, 1000);
    self->mapView.region = reg;
    MKPointAnnotation* ann = [[MKPointAnnotation alloc] init];
    ann.coordinate = loc;
    ann.title = [cgNameArray objectAtIndex:i];
    ann.subtitle = [cgLocArray objectAtIndex:i];
    NSMutableArray *mutAnnArray = [NSMutableArray arrayWithArray:annArray];
    [mutAnnArray addObject:ann];
 }
}

最佳答案

您正在循环内创建一个可变数组并将对象添加到其中。

在循环的下一次迭代中，您将创建一个新的可变数组，并为其添加新的注释。

抛开您正在从另一个数组创建它的事实，而不只是将注释添加到annArray

基本上，要添加对象的数组将持续一次迭代，然后超出范围。

尝试将数组移出循环：

-(void)plotMultipleLocs {
    float latitude;
    float longitude;
    NSRange commaIndex;
    NSString *coordGroups;

    NSMutableArray *mutAnnArray = [NSMutableArray arrayWithArray:annArray]; // Create one array outside the loop.

    for (int i=0; i<=cgIdArray.count; i++) {
        coordGroups = [cgInAreaArray objectAtIndex:i];
        commaIndex = [coordGroups rangeOfString:@","];
        latitude = [[coordGroups substringToIndex:commaIndex.location] floatValue];
        longitude = [[coordGroups substringFromIndex:commaIndex.location + 1] floatValue];
        CLLocationCoordinate2D loc = CLLocationCoordinate2DMake(latitude, longitude);
         MKCoordinateRegion reg = MKCoordinateRegionMakeWithDistance(loc, 1000, 1000);
         self->mapView.region = reg;
         MKPointAnnotation* ann = [[MKPointAnnotation alloc] init];
         ann.coordinate = loc;
         ann.title = [cgNameArray objectAtIndex:i];
         ann.subtitle = [cgLocArray objectAtIndex:i];
        [mutAnnArray addObject:ann]; // Add the annotation to the single array.
    }

// mutAnnArray will go out of scope here, so maybe return it, or assign it to a property
}

关于iphone - NSMutableArray似乎过早发布，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/9039468/