编译时出现“Invalid initializer”错误答案

【问题标题】："Invalid initializer" error when compiling编译时出现“Invalid initializer”错误
【发布时间】：2011-08-16 11:19:47
【问题描述】：

我用这个代码

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

    // Override point for customization after application launch.

    [self.window makeKeyAndVisible];

    // position is a number between 0 and 1, where 0 gives the start position, and 1 gives the end position

    CLLocationCoordinate2D startPoint = CLLocationCoordinate2DMake(37.9,-122.5);
    CLLocationCoordinate2D endPoint = CLLocationCoordinate2DMake(37.188022,-122.39979);

    for (int i = 1; i < 5; i++) {
        float position = i / 5.0;
    CLLocationCoordinate2D middlePosition =  [self pointBetweenStartPoint:startPoint endPoint:endPoint position:position];
    NSLog("%f, %f", middlePosition.latitude, middlePosition.longitude);
    }

    return YES;
}

- (CLLocationCoordinate2D)pointBetweenStartPoint:(CLLocationCoordinate2D)startPoint endPoint:(CLLocationCoordinate2D)endPoint position:(float)position {

    CLLocationDegrees latSpan = endPoint.latitude - startPoint.latitude;
    CLLocationDegrees longSpan = endPoint.longitude - startPoint.longitude;

    CLLocationCoordinate2D ret = CLLocationCoordinate2DMake(startPoint.latitude + latSpan*position,
startPoint.longitude + longSpan*position);
    return ret;
}

并收到此错误：此行中的初始化程序无效

CLLocationCoordinate2D middlePosition = [self pointBetweenStartPoint:startPoint endPoint:endPoint position:position];

如何删除？

【问题讨论】：

标签： iphone xcode view cllocationmanager cllocation

【解决方案1】：

在您引用的代码块之前是否有 pointBetweenStartPoint:endPoint:position: 可见的前向声明（例如，来自导入的头文件）？如果不是，编译器将假定该方法返回 id，这对于初始化 CLLocationCoordinate2D 结构无效，并给出该错误。

【讨论】：