iOS中屏幕亮度与闪光灯控制详解

本文主要介绍的是关于ios屏幕亮度与闪光灯控制的相关内容，分享出来供大家参考学习，下面来看看详细的介绍：

所用涉及框架：avfoundation框架和imageio

读取屏幕亮度： [uiscreen mainscreen].brightness;

设置屏幕亮度： [[uiscreen mainscreen] setbrightness:0.5];

获取环境亮度主要代码：

- (void)gettorch {
 avcapturedevice *device = [avcapturedevice defaultdevicewithmediatype:avmediatypevideo];
 avcapturedeviceinput *input = [[avcapturedeviceinput alloc]initwithdevice:device error:nil];
 avcapturevideodataoutput *output = [[avcapturevideodataoutput alloc] init];
 [output setsamplebufferdelegate:self queue:dispatch_get_main_queue()];
 self.session = [[avcapturesession alloc]init];
 [self.session setsessionpreset:avcapturesessionpresethigh];
 if ([self.session canaddinput:input]) {
  [self.session addinput:input];
 }
 if ([self.session canaddoutput:output]) {
  [self.session addoutput:output];
 }
 [self.session startrunning];

}

- (void)captureoutput:(avcaptureoutput*)captureoutput didoutputsamplebuffer:(cmsamplebufferref)samplebuffer fromconnection:(avcaptureconnection*)connection {
 cfdictionaryref metadatadict =cmcopydictionaryofattachments(null,samplebuffer, 
 kcmattachmentmode_shouldpropagate);
 nsdictionary *metadata = [[nsmutabledictionary alloc] initwithdictionary:
 (__bridgensdictionary*)metadatadict];

 cfrelease(metadatadict);
 nsdictionary *exifmetadata = [[metadata objectforkey:(nsstring*)kcgimagepropertyexifdictionary] mutablecopy];
 float brightnessvalue = [[exifmetadata objectforkey:(nsstring*)kcgimagepropertyexifbrightnessvalue] floatvalue];
 nslog(@"%f",brightnessvalue);
 // 根据brightnessvalue的值来打开和关闭闪光灯
 avcapturedevice*device = [avcapturedevice defaultdevicewithmediatype:avmediatypevideo];
 bool result = [device hastorch];// 判断设备是否有闪光灯
 if((brightnessvalue <0) && result) {
 // 打开闪光灯
  [device lockforconfiguration:nil];
  [device settorchmode:avcapturetorchmodeon];//开
  [device unlockforconfiguration];
 }else if((brightnessvalue >0) && result) {
 // 关闭闪光灯
  [device lockforconfiguration:nil];  
  [device settorchmode:avcapturetorchmodeoff];//关
  [device unlockforconfiguration]; 
 }
}

总结

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