Question

我正在尝试将此代码转换为Swift 2.2。但我收到此错误。

这是目标 - C代码

- (NSDictionary *)parseLatLonFile:(NSString *)fileName
{
    NSMutableDictionary *ret = [NSMutableDictionary new];
    NSString *path = [[NSBundle mainBundle] pathForResource:fileName
                                                     ofType:@"txt"];
    NSString *content = [NSString stringWithContentsOfFile:path
                                                  encoding:NSUTF8StringEncoding
                                                     error:NULL];
    NSArray *lines = [content componentsSeparatedByString:@"\n"];
    for (NSString *line in lines) {
        NSArray *parts = [line componentsSeparatedByString:@","];
        NSString *latStr = parts[0];
        NSString *lonStr = parts[1];

    CLLocationDegrees latitude = [latStr doubleValue];
    CLLocationDegrees longitude = [lonStr doubleValue];

    // For this example, each location is weighted equally
    double weight = 1;

    CLLocation *location = [[CLLocation alloc] initWithLatitude:latitude
                                                      longitude:longitude];
    MKMapPoint point = MKMapPointForCoordinate(location.coordinate);
    NSValue *pointValue = [NSValue value:&point
                            withObjCType:@encode(MKMapPoint)];
    ret[pointValue] = @(weight);
}

return ret;
}

这是我的转换代码

func parseLatLonFile(fileName: String) -> [NSObject : AnyObject] {
    var ret = [NSObject : AnyObject]()
    var path = NSBundle.mainBundle().pathForResource(fileName, ofType: "txt")!
    var content = try! String(contentsOfFile: path, encoding:NSUTF8StringEncoding)
    var lines = content.componentsSeparatedByString("\n")
    for line: String in lines {
        var parts = line.componentsSeparatedByString(",")
        var latStr = parts[0]
        var lonStr = parts[1]
        var latitude = CDouble(latStr)!
        var longitude = CDouble(lonStr)!
        // For this example, each location is weighted equally
        var weight: Double = 1
        var location = CLLocation(latitude: latitude, longitude: longitude)
        var point = MKMapPointForCoordinate(location.coordinate)
        var pointValue = NSValue.value(point, withObjCType: !)
        ret[pointValue!] = weight
    }
    return ret
}

我正在尝试使用此库来显示热图： https://github.com/dataminr/DTMHeatmap

我正在将此转换为Swift，因为我真的想了解这是如何工作的。

有任何帮助吗？如果在swift中有一些热图示例是可能的，欢迎所有帮助。我正在尝试获取kml数据并解析它。

Answer 1

原始代码似乎是将MKMapPoint（结构）实例转换为NSValue（类）实例，以便将其用作字典键。

原因在于，在Objective-C中，字典键/值（和数组元素）只能是引用类型对象（类实例），而不是值类型对象（struct instance，int，double等... ）。

对于Swift词典（和数组），没有这样的约束：~~你可以使用类型为MKMapPoint~~ 的键的字典，因此不需要使用{{1} }。

编辑：结果NSValue 不符合协议MKMapPoint，因此您无法使用类型作为字典的键;我的错误。

您可以将Hashable实例转换为字符串，然后使用它。例如：

MKMapPoint

Answer 2

试用此代码。

func parseLatLonFile(_ fileName: String) -> [AnyHashable: Any] {
    var ret = [AnyHashable: Any]()
    let path: String? = Bundle.main.path(forResource: fileName, ofType: "txt")
    let content = try? String(contentsOfFile: path!, encoding: String.Encoding.utf8)
    let lines: [Any]? = content?.components(separatedBy: "\n")
    for line: String in lines as! [String] {
        let parts: [Any] = line.components(separatedBy: ",")
        let latStr: String = parts[0] as! String
        let lonStr: String = parts[1] as! String
        let latitude: CLLocationDegrees =  Double(latStr)!
        let longitude: CLLocationDegrees = Double(lonStr)!

        // For this example, each location is weighted equally
        let weight: Double = 1
        let location = CLLocation(latitude: latitude, longitude: longitude)
        var point: MKMapPoint = MKMapPointForCoordinate(location.coordinate)
        let type = NSValue(mkCoordinate: location.coordinate).objCType
        let pointValue = NSValue(&point, withObjCType: type)

        ret[pointValue] = (weight)
    }

    return ret

}

将以下代码转换为Swift 2.2

2 个答案: