启用导航并将出行方式设置为驾车后，iOS 版 Navigation SDK 会在地图左下角显示一个速度限制控件，用于显示当前速度限制。如果驾驶员超过限速，该控件会展开，在限速显示屏旁边显示速度计，并在限速达到特定阈值时触发提醒。
默认情况下，当驾驶员超过速度限制 5 英里/小时（或 10 公里/小时）时，Navigation SDK 会触发一条轻微速度提醒，并将速度计文本的颜色更改为红色。当驾驶员超过限速 10 英里/小时（或 20 公里/小时）时，该功能会触发主要速度提醒，并将速度计的背景颜色更改为红色。
您可以自定义触发提醒的阈值，以及速度计显示的文本和背景颜色。您还可以使用 Navigation SDK 提供驾驶员的速度信息。例如，您可以向拼车运营商提供速度信息，以鼓励他们遵守限速信息并提高安全性。
自定义速度提醒阈值
您可以将次要和主要速度提醒的速度提醒阈值自定义为当前速度限制的百分比。您还可以指定超过阈值多长时间之后地图显示提醒。
以下代码示例将次要速度提醒的阈值设置为超出速度限制的 5%，并将主要速度提醒的阈值设置为超出速度限制的 10%。它指定地图在超出提醒阈值 5 秒后显示提醒。
Swift
let minorSpeedAlertThresholdPercentage: CGFloat = 0.05 let
majorSpeedAlertThresholdPercentage: CGFloat = 0.1 let
severityUpgradeDurationSeconds: TimeInterval = 5
// Configure SpeedAlertOptions let mutableSpeedAlertOptions:
GMSNavigationMutableSpeedAlertOptions = GMSNavigationMutableSpeedAlertOptions()
mutableSpeedAlertOptions.setSpeedAlertThresholdPercentage(minorSpeedAlertThresholdPercentage,
for: .minor)
mutableSpeedAlertOptions.setSpeedAlertThresholdPercentage(majorSpeedAlertThresholdPercentage,
for: .major) mutableSpeedAlertOptions.severityUpgradeDurationSeconds =
severityUpgradeDurationSeconds
// Set SpeedAlertOptions to Navigator. mapView.navigator?.speedAlertOptions =
mutableSpeedAlertOptions; mapView.navigator?.add(self); // Only needed if
listening to the delegate events.
Objective-C
static const CGFloat minorSpeedAlertThresholdPercentage = 0.05; static const
CGFloat majorSpeedAlertThresholdPercentage = 0.1; static const NSTimeInterval
severityUpgradeDurationSeconds = 5;
// Configure SpeedAlertOptions GMSNavigationMutableSpeedAlertOptions
*mutableSpeedAlertOptions = [[GMSNavigationMutableSpeedAlertOptions alloc]
init]; [mutableSpeedAlertOptions setSpeedAlertThresholdPercentage:
minorSpeedAlertThresholdPercentage
forSpeedAlertSeverity:GMSNavigationSpeedAlertSeverityMinor];
[mutableSpeedAlertOptions
setSpeedAlertThresholdPercentage:majorSpeedAlertThresholdPercentage
forSpeedAlertSeverity:GMSNavigationSpeedAlertSeverityMajor];
[mutableSpeedAlertOptions
setSeverityUpgradeDurationSeconds:severityUpgradeDurationSeconds];
// Set SpeedAlertOptions to Navigator. mapView.navigator.speedAlertOptions =
mutableSpeedAlertOptions; [mapView.navigator addListener:self]; // Only needed
if listening to the delegate events.
自定义速度计显示速度提醒的方式
您可以为每个警报等级自定义速度计显示的颜色。
下表显示了 GMSNavigationSpeedometerUIOptions 类中速度提醒的默认颜色：
| 元素 | 颜色 |
|---|---|
| MinorSpeedAlertBackgroundColorDayMode | 0xffffff(白色) |
| MinorSpeedAlertBackgroundColorNightMode | 0x000000 |
| MinorSpeedAlertTextColorDayMode | 0xd93025 |
| MinorSpeedAlertTextColorNightMode | 0xd93025 |
| MajorSpeedAlertBackgroundColorDayMode | 0xd93025 |
| MajorSpeedAlertBackgroundColorNightMode | 0xd93025 |
| MajorSpeedAlertTextColorDayMode | 0xffffff(白色) |
| MajorSpeedAlertTextColorNightMode | 0xffffff(白色) |
您可以为次要和主要速度提醒指定速度计的文本和背景颜色：
Swift
let mutableSpeedometerUIOptions: GMSNavigationMutableSpeedometerUIOptions =
GMSNavigationMutableSpeedometerUIOptions()
mutableSpeedometerUIOptions.setTextColor(minorSpeedAlertTextColor, for: .minor,
lightingMode: .normal)
mutableSpeedometerUIOptions.setTextColor(majorSpeedAlertTextColor, for: .major,
lightingMode: .normal)
mutableSpeedometerUIOptions.setBackgroundColor(minorSpeedAlertNightModeBackgroundColor,
for: .minor, lightingMode: .lowLight)
mutableSpeedometerUIOptions.setBackgroundColor(majorSpeedAlertDayModeBackgroundColor,
for: .major, lightingMode: .normal)
mapView.settings.speedometerUIOptions = mutableSpeedometerUIOptions
Objective-C
GMSNavigationMutableSpeedometerUIOptions *mutableSpeedometerUIOptions =
[[GMSNavigationMutableSpeedometerUIOptions alloc] init];
[mutableSpeedometerUIOptions setTextColor: minorSpeedAlertTextColor
forSpeedAlertSeverity: GMSNavigationSpeedAlertSeverityMinor lightingMode:
GMSNavigationLightingModeNormal]; [mutableSpeedometerUIOptions setTextColor:
majorSpeedAlertTextColor forSpeedAlertSeverity:
GMSNavigationSpeedAlertSeverityMajor lightingMode:
GMSNavigationLightingModeNormal]; [mutableSpeedometerUIOptions
setBackgroundColor: minorSpeedAlertNightModeBackgroundColor
forSpeedAlertSeverity: GMSNavigationSpeedAlertSeverityMinor lightingMode:
GMSNavigationLightingModeLowLight]; [mutableSpeedometerUIOptions
setBackgroundColor: majorSpeedAlertDayModeBackgroundColor forSpeedAlertSeverity:
GMSNavigationSpeedAlertSeverityMajor
lightingMode:GMSNavigationLightingModeNormal];
mapView.settings.speedometerUIOptions = mutableSpeedometerUIOptions;
正在从司机处接收速度信息
如果您的应用需要分享有关驾驶员速度的信息，您还可以使用 Navigation SDK 提供驾驶员的速度信息。这对于拼车应用非常有用，在此类应用中，运营商可能希望监控驾驶员的超速以提升安全性。
例如，以下示例可在速度超过速度限制的指定百分比时共享速度信息：
Swift
// Listener method for sharing speed information when the speed exceeds the
speed limit by a specified percentage. #pragma mark GMSNavigatorListener func
navigator(_ navigator : GMSNavigator, didUpdateSpeedingPercentage
percentageAboveLimit : Float) { ... }
Objective-C
// Listener method listening to speeding feed. #pragma mark
GMSNavigatorListener - (void)navigator:(GMSNavigator *)navigator
didUpdateSpeedingPercentage:(float)percentageAboveLimit { ... }