覆盖接近传感器时保持显示

Question

我想在不关闭显示屏的情况下拦截接近传感器.

我从文档中知道我有两个Bool变量:

proximityMonitoringEnabled
proximityState

和这段代码

[UIDevice currentDevice].proximityMonitoringEnabled = YES;

当接近传感器检测到某些东西时,它会关闭显示屏,就像在打电话时将手机放在耳边一样.

覆盖接近传感器时如何保持显示屏开启？

Answer 1

Apple的文档指出"并非所有iPhone OS设备都有接近传感器."要确定您的应用程序运行的设备是否支持接近监控,请将proximityMonitoringEnabled属性设置为YES,然后检查其值:

UIDevice *device = [UIDevice currentDevice];
[device setProximityMonitoringEnabled:YES];

if (device.proximityMonitoringEnabled == YES) {
    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(proximityChanged:) 
                                                 name:@"UIDeviceProximityStateDidChangeNotification"
                                               object:device];
}

- (void) proximityChanged:(NSNotification *)notification {
    UIDevice *device = [notification object];
    NSLog(@"In proximity: %i", device.proximityState);
}

资料来源:http://www.whatsoniphone.com/blog/new-in-iphone-30-tutorial-series-part-4-proximity-detection/

将有助于检测传感器的当前状态.

允许屏幕变暗的公共API:

[UIScreen mainScreen].wantsSoftwareDimming = YES;
[UIScreen mainScreen].brightness = $your_brightness_value;

在此处找到:在iOS 6中更改为wantsSoftwareDimming？

Answer 2

在阅读了关于该主题的不同论坛后,目前我们无法在公共API中阻止iPhone屏幕在覆盖接近传感器时变黑.您可以对传感器做的唯一事情就是告诉它何时被覆盖或不通过通知中心,但再次无法控制其自然行为(当它使屏幕变暗/变黑时).

Answer 3

尽管没有公共 API 来执行此操作，但您可以挂接到IOKit'sIOHIDEventSystem并侦听屏幕变暗通知：

// Create and open an event system.
IOHIDEventSystemRef system = IOHIDEventSystemCreate(NULL);

// Set the PrimaryUsagePage and PrimaryUsage that the AppleProxShim service uses
int page = 65280;
int usage = 8;

// Create a dictionary to match the service with
CFStringRef keys[2];
CFNumberRef nums[2];
keys[0] = CFStringCreateWithCString(0, "PrimaryUsagePage", 0);
keys[1] = CFStringCreateWithCString(0, "PrimaryUsage", 0);
nums[0] = CFNumberCreate(0, kCFNumberSInt32Type, &page);
nums[1] = CFNumberCreate(0, kCFNumberSInt32Type, &usage);
CFDictionaryRef dict = CFDictionaryCreate(0, (const void**)keys, (const void**)nums, 2, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
// Get the total of matching services with the above criteria
CFArrayRef srvs = (CFArrayRef)IOHIDEventSystemCopyMatchingServices(system, dict, 0, 0, 0, 0);

// Get the service
IOHIDServiceRef serv = (IOHIDServiceRef)CFArrayGetValueAtIndex(srvs, 0);
int interval = 1 ;

// Set an interval of 1 , to activate the sensor  
IOHIDServiceSetProperty((IOHIDServiceRef)serv, CFSTR("ReportInterval"), CFNumberCreate(0, kCFNumberSInt32Type, &interval));

// add your event handler
IOHIDEventSystemOpen(system, handle_event, NULL, NULL, NULL);
int defaultInterval = 0;
IOHIDServiceSetProperty((IOHIDServiceRef)serv, CFSTR("ReportInterval"), CFNumberCreate(0, kCFNumberSInt32Type, &defaultInterval));

// close handles and release the IOHIDEventSystemRef
IOHIDEventSystemClose(system, NULL);
CFRelease(system);

您的事件处理函数指针将如下所示：

void handle_event(void* target, void* refcon, IOHIDServiceRef service, IOHIDEventRef event) {
    if (IOHIDEventGetType(event) == kIOHIDEventTypeProximity) { // Proximity Event Received
        // not necessary, but if you want the value from the sensor, get it from IOHIDEventGetIntegerValue
        int proximityValue = IOHIDEventGetIntegerValue(event, (IOHIDEventField)kIOHIDEventFieldProximityDetectionMask); // Get the value of the ProximityChanged Field (0 or 64)

        // Call dimScreen with the boolean NO
        int (*SBSSpringBoardServerPort)() = (int (*)())dlsym(RTLD_DEFAULT, "SBSSpringBoardServerPort");
        int port = SBSSpringBoardServerPort(); 
        void (*_SBDimScreen)(int _port,BOOL shouldDim) = (void (*)(int _port,BOOL shouldDim))dlsym(RTLD_DEFAULT, "SBDimScreen");

        // This is where the logic to dim the screen based on the sensor value would go.  In this case, I'm hardcoding NO instead of the value of proximityValue from above
        // BOOL dim = proximityValue == 0 ? NO : YES;
        _SBDimScreen(port, NO); 
    }
}

_SBDimScreen甚至可能不需要调用，因为具有空函数指针可能会停止所有接近传感器事件。

从iPhoneDevWiki上AppleProxShim页面上的命令行工具示例修改的代码。