ios - 无法识别的选择器发送到实例错误 - 我的错误在哪里？

Question

我不确定我的代码有什么问题。以下是我可能有问题的 3 个函数。这是一款适用于 iOS 的 Google map 应用。

错误消息:由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因:“-[__NSArrayI floatValue]:无法识别的选择器发送到实例 0x60000042e680”

     - (void)drawPolygon{
    GMSMutablePath *rect = [GMSMutablePath path];
    for (int i = 0; i <= [tappedCoordinates count]-1; i++) {
    event.latitude = [[tappedCoordinates objectAtIndex:i] floatValue];
    event.longitude = [[tappedCoordinates objectAtIndex:i] floatValue];
    [rect addCoordinate:event];
}
// first tapped point to connect with last point in order to close the polygon.
event.latitude = [[tappedCoordinates objectAtIndex:0] floatValue];
event.longitude = [[tappedCoordinates objectAtIndex:0] floatValue];
[rect addCoordinate:event];
...
}

  - (void)addMarker{
for (int i = 0; i <= [tappedCoordinates count]-1; i++) {
position.latitude = [[[tappedCoordinates objectAtIndex:i] objectAtIndex:0] floatValue];
position.longitude = [[[tappedCoordinates objectAtIndex:i] objectAtIndex:1] floatValue];
...
}

Answer 1

您只是没有深入到数组中以获取实际的 long/lat 值:

for (int i = 0; i <= [tappedCoordinates count]-1; i++) {
    event.latitude = [[[tappedCoordinates objectAtIndex:i] objectAtIndex:0] floatValue];
    event.longitude = [[[tappedCoordinates objectAtIndex:i] objectAtIndex:1] floatValue];
    [rect addCoordinate:event];
}

event.latitude = [[[tappedCoordinates objectAtIndex:0] objectAtIndex:0] floatValue];
event.longitude = [[[tappedCoordinates objectAtIndex:0] objectAtIndex:1] floatValue];

编辑:只是为了澄清 - [tappedCoordinates objectAtIndex:0] 是一个 NSArray。当您在其上调用 floatValue 时，NSArray 不知道该怎么做，因为它不是数值。此外，您的方法的替代方法是拥有一个 CGPoint 对象数组(比嵌套数组更好的实现):

NSMutableArray *coords = [NSMutableArray new];
CGPoint coord = CGPointMake(1.5f, 2.5f);
[coords addObject:[NSValue valueWithCGPoint: coord]];

CGPoint storedCoord = [[coords objectAtIndex:0] CGPointValue];
NSLog (@"Lat: %f, long: %f", storedCoord.x, storedCoord.y);

您甚至可以更进一步，创建一个子类 CGPoint(名为 Coordinate)，它具有纬度和经度属性，可以分别返回 x 和 y(主要是为了可读性)。