iOS 15 CLLocation 读取 sourceInformation 崩溃

iOS 15 之后，Apple 终于开放了相关读取 GPS 信息来源的 API:

@interface CLLocationSourceInformation : NSObject <NSCopying, NSSecureCoding>

/*
 * isSimulatedBySoftware
 *
 * Discussion:
 * Set to YES if this location was detected as being generated by a software simulator, such as Xcode
 */
@property(readonly, nonatomic) BOOL isSimulatedBySoftware;

/*
 * isProducedByAccessory
 *
 * Discussion:
 *  Set to YES if this location was generated from an external accessory, such as CarPlay or an MFi accessory
 */
@property(readonly, nonatomic) BOOL isProducedByAccessory;
@end

CLLocation 新增 CLLocationSourceInformation 类型的 sourceInformation 属性，标识是软件生成的（isSimulatedBySoftware == true）还是 GPS 外设生成的（isProducedByAccessory == true）。示例代码如下：

if (@available(iOS 15.0, *)) {
    BOOL isSimulatedBySoftware = location.sourceInformation.isSimulatedBySoftware;
    BOOL isProducedByAccessory = location.sourceInformation.isProducedByAccessory;
}

但这个代码如果实际在线上运行，会发现存在部分的 iOS 15 设备直接 Crash 的情况:

-[CLLocation sourceInformation]: unrecognized selector sent to instance ...

问题的原因是，虽然 API 文档表明了这是一个在 iOS 15 及以上系统中可用的 API，但实际上是在 iOS 15 beta3 才开始生效的，这就导致上述代码运行在 iOS 15 beta1 或 iOS 15 beta2 系统上，就会产生找不到 sourceInformation selector 的崩溃。为了兼容这部分系统，改进的修复方案如下：

if (@available(iOS 15.0, *)) {
    if ([location respondsToSelector:@selector(sourceInformation)]) {
        BOOL isSimulatedBySoftware = location.sourceInformation.isSimulatedBySoftware;
        BOOL isProducedByAccessory = location.sourceInformation.isProducedByAccessory;
    }
}

不过话说回来，能使用 beta 系统且迟迟不更新的大概也不是正经用户吧😊。