IOS打开系统相机的闪光灯

ios有两种的拍照和视频的方式：

1.直接使用uiimagepickercontroller，这个类提供了一个简单便捷的拍照与选择图片库里图片的功能。

2.另一种是通过avfoundation.framework框架完全自定义拍照的界面和选择图片库界面。我只做了第一种，就先给大家介绍第一种做法：

一、首先调用接口前，我们需要先判断当前设备是否支持uiimagepickercontroller，用issourcetypeavailable:来判断是否可用

二、查看符合的媒体类型，这个时候我们调用availablemediatypeforsourcetype：判断

在调用uiimagepickercontroller时我们需要加入他的两个代理方法：

uinavigationcontrollerdelegate和uiimagepickercontrollerdelegate，在调用摄像头的时候还可以调闪光灯，一会代码里有。

要调用闪光灯需要先建一个avcapturesession类的实例对象:

//  created by 张茫原 on 13-1-23.
//  copyright (c) 2013年 张茫原. all rights reserved.
//
 
#import <uikit/uikit.h>
//调用闪光灯调用框架
#import <avfoundation/avfoundation.h>
 
@interface cameraviewcontroller : uiviewcontroller<uinavigationcontrollerdelegate, uiimagepickercontrollerdelegate>
{
    avcapturesession * _avsession;//调用闪光灯的时候创建的类
}
 
@property(nonatomic,retain)avcapturesession * avsession;
 
@end

在.m的- (void)viewdidload里建立4button，camera调用相机、library调用图片库、flashlight打开闪光灯、close关闭闪光灯,这里创建button的代码我就不再写了。

//打开相机
-(void)addcarema
{
    //判断是否可以打开相机，模拟器此功能无法使用
    if ([uiimagepickercontroller issourcetypeavailable:uiimagepickercontrollersourcetypecamera]) {
        
        uiimagepickercontroller * picker = [[uiimagepickercontroller alloc]init];
        picker.delegate = self;
        picker.allowsediting = yes;  //是否可编辑
        //摄像头
        picker.sourcetype = uiimagepickercontrollersourcetypecamera;
        [self presentmodalviewcontroller:picker animated:yes];
        [picker release];
    }else{
        //如果没有提示用户
        uialertview *alert = [[uialertview alloc] initwithtitle:@"error" message:@"你没有摄像头" delegate:nil cancelbuttontitle:@"drat!" otherbuttontitles:nil];
        [alert show];
    }
}

打开相机后，然后需要调用uiimagepickercontrollerdelegate里的方法，拍摄完成后执行的方法和点击cancel之后执行的方法：

//拍摄完成后要执行的方法
-(void)imagepickercontroller:(uiimagepickercontroller *)picker didfinishpickingmediawithinfo:(nsdictionary *)info
{
    //得到图片
    uiimage * image = [info objectforkey:uiimagepickercontrolleroriginalimage];
    //图片存入相册
    uiimagewritetosavedphotosalbum(image, nil, nil, nil);
    [self dismissmodalviewcontrolleranimated:yes];
}
//点击cancel按钮后执行方法
-(void)imagepickercontrollerdidcancel:(uiimagepickercontroller *)picker
{
    [self dismissmodalviewcontrolleranimated:yes];
}

调用相机照片和保存到图片库已经完成。

接着介绍打开照片库：

-(void)openpiclibrary
{
    //相册是可以用模拟器打开的
    if ([uiimagepickercontroller issourcetypeavailable:uiimagepickercontrollersourcetypephotolibrary]) {
        uiimagepickercontroller * picker = [[uiimagepickercontroller alloc]init];
        picker.delegate = self;
        picker.allowsediting = yes;//是否可以编辑
        //打开相册选择照片
        picker.sourcetype = uiimagepickercontrollersourcetypephotolibrary;
        [self presentmodalviewcontroller:picker  animated:yes];
        [picker release];
    }else{
        uialertview *alert = [[uialertview alloc] initwithtitle:@"error" message:@"你没有摄像头" delegate:nil cancelbuttontitle:@"drat!" otherbuttontitles:nil];
        [alert show];
    }
}
//选中图片进入的代理方法
-(void)imagepickercontroller:(uiimagepickercontroller *)picker didfinishpickingimage:(uiimage *)image editinginfo:(nsdictionary *)editinginfo
{
    [self dismissmodalviewcontrolleranimated:yes];
}

调用闪光灯的代码，由于我也不是很理解，所以没法加注释，但是已经亲测可用，但是调闪光灯时有一个算是bug吧，闪光灯会闲一下，然后再一直亮

-(void)openflashlight
{
    avcapturedevice * device = [avcapturedevice defaultdevicewithmediatype:avmediatypevideo];
    if (device.torchmode == avcapturetorchmodeoff) {
        //create an av session
        avcapturesession * session = [[avcapturesession alloc]init];
        // create device input and add to current session
        avcapturedeviceinput * input = [avcapturedeviceinput deviceinputwithdevice:device error:nil];
        [session addinput:input];
        // create video output and add to current session
        avcapturevideodataoutput * output = [[avcapturevideodataoutput alloc]init];
        [session addoutput:output];
        // start session configuration
        [session beginconfiguration];
        [device lockforconfiguration:nil];
        // set torch to on
        [device settorchmode:avcapturetorchmodeon];
        [device unlockforconfiguration];
        [session commitconfiguration];
        // start the session
        [session startrunning];
        // keep the session around
        [self setavsession:self.avsession];
        [output release];
    }
}
-(void)closeflashlight
{
    [self.avsession stoprunning];
    [self.avsession release];
}

以上所述就是本文的全部内容了，希望大家能够喜欢。