Question

我正在尝试使用文件中的路线绘制地图。我正在尝试通过关注此博客（http://spitzkoff.com/craig/?p=108）来学习此过程。

当进程命中我的函数时，它会终止（我在下面给出了错误消息）

- (void) drawRoute {
//
// load the points from our local resource
//
NSString* filePath = [[NSBundle mainBundle] pathForResource:@"route" ofType:@"csv"];
NSString* fileContents = [NSString stringWithContentsOfFile:filePath];
NSArray* pointStrings = [fileContents componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

NSMutableArray* points = [[NSMutableArray alloc] initWithCapacity:pointStrings.count];

for(int idx = 0; idx < pointStrings.count; idx++)
{
    // break the string down even further to latitude and longitude fields. 
    NSString* currentPointString = [pointStrings objectAtIndex:idx];
    NSArray* latLonArr = [currentPointString componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@","]];

    CLLocationDegrees latitude  = [[latLonArr objectAtIndex:0] doubleValue];
    CLLocationDegrees longitude = [[latLonArr objectAtIndex:1] doubleValue];

    CLLocation* currentLocation = [[[CLLocation alloc] initWithLatitude:latitude longitude:longitude] autorelease];
    [points addObject:currentLocation];
}

// CREATE THE ANNOTATIONS AND ADD THEM TO THE MAP

// first create the route annotation, so it does not draw on top of the other annotations. 
CSRouteAnnotation* routeAnnotation = [[[CSRouteAnnotation alloc] initWithPoints:points] autorelease];
[secondMap addAnnotation:routeAnnotation];


// create the rest of the annotations
CSMapAnnotation* annotation = nil;

// create the start annotation and add it to the array
annotation = [[[CSMapAnnotation alloc] initWithCoordinate:[[points objectAtIndex:0] coordinate]
                                           annotationType:CSMapAnnotationTypeStart
                                                    title:@"Start Point"] autorelease];
[secondMap addAnnotation:annotation];


// create the end annotation and add it to the array
annotation = [[[CSMapAnnotation alloc] initWithCoordinate:[[points objectAtIndex:points.count - 1] coordinate]
                                           annotationType:CSMapAnnotationTypeEnd
                                                    title:@"End Point"] autorelease];
[secondMap addAnnotation:annotation];


[points release];

// center and size the map view on the region computed by our route annotation. 
[secondMap setRegion:routeAnnotation.region];

}

错误讯息：

    [Session started at 2010-07-30 01:22:13 -0400.]
2010-07-30 01:22:19.078 ActualTry[4893:20b] Found center of new Route Annotation at 0.000000, 0
2010-07-30 01:22:19.079 ActualTry[4893:20b] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSCFArray objectAtIndex:]: index (0) beyond bounds (0)'
2010-07-30 01:22:19.080 ActualTry[4893:20b] Stack: (
    807902715,
    2492862011,
    807986683,
    807986522,
    810976489,
    810572359,
    13379,
    12278,
    10121,
    814709201,
    815110321,
    815119058,
    815114270,
    814813151,
    814722763,
    814748641,
    839148405,
    807687520,
    807683624,
    839142449,
    839142646,
    814752238,
    9380,
    9234
)

如果有人可以帮助我，我将非常感激。我知道这是基本的gdb调试，但我无法解决这个问题。

谢谢。

Answer 1

错误消息表明您正在尝试访问阵列中不存在的对象。看看你的代码，似乎pointStrings数组是空的。你确定你的csv文件有数据吗？尝试使用NSlog打印pointStrings。

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