iOS开发技巧之自定义相机

最近公司的项目中用到了相机，由于不用系统的相机，ui给的相机切图，必须自定义才可以。就花时间简单研究了一下相机的自定义。

相机属于系统硬件，这就需要我们来手动调用iphone的相机硬件，分为以下步骤：

1、首先声明以下对象

#import <avfoundation/avfoundation.h>
//捕获设备，通常是前置摄像头，后置摄像头，麦克风（音频输入）
@property (nonatomic, strong) avcapturedevice *device;
 
//avcapturedeviceinput 代表输入设备，他使用avcapturedevice 来初始化
@property (nonatomic, strong) avcapturedeviceinput *input;
 
//输出图片
@property (nonatomic ,strong) avcapturestillimageoutput *imageoutput;
 
//session：由他把输入输出结合在一起，并开始启动捕获设备（摄像头）
@property (nonatomic, strong) avcapturesession *session;
 
//图像预览层，实时显示捕获的图像
@property (nonatomic ,strong) avcapturevideopreviewlayer *previewlayer;

2、初始化各个对象

- (void)cameradistrict
{
// avcapturedevicepositionback 后置摄像头
// avcapturedevicepositionfront 前置摄像头
 self.device = [self camerawithposition:avcapturedevicepositionfront];
 self.input = [[avcapturedeviceinput alloc] initwithdevice:self.device error:nil];
 
 self.imageoutput = [[avcapturestillimageoutput alloc] init];
 
 self.session = [[avcapturesession alloc] init];
 //  拿到的图像的大小可以自行设定
 // avcapturesessionpreset320x240
 // avcapturesessionpreset352x288
 // avcapturesessionpreset640x480
 // avcapturesessionpreset960x540
 // avcapturesessionpreset1280x720
 // avcapturesessionpreset1920x1080
 // avcapturesessionpreset3840x2160
 self.session.sessionpreset = avcapturesessionpreset640x480;
 //输入输出设备结合
 if ([self.session canaddinput:self.input]) {
  [self.session addinput:self.input];
 }
 if ([self.session canaddoutput:self.imageoutput]) {
  [self.session addoutput:self.imageoutput];
 }
 //预览层的生成
 self.previewlayer = [[avcapturevideopreviewlayer alloc] initwithsession:self.session];
 self.previewlayer.frame = cgrectmake(0, 64, screen_width, screen_height-64);
 self.previewlayer.videogravity = avlayervideogravityresizeaspectfill;
 [self.view.layer addsublayer:self.previewlayer];
 //设备取景开始
 [self.session startrunning];
 if ([_device lockforconfiguration:nil]) {
 //自动闪光灯，
  if ([_device isflashmodesupported:avcaptureflashmodeauto]) {
   [_device setflashmode:avcaptureflashmodeauto];
  }
  //自动白平衡,但是好像一直都进不去
  if ([_device iswhitebalancemodesupported:avcapturewhitebalancemodeautowhitebalance]) {
   [_device setwhitebalancemode:avcapturewhitebalancemodeautowhitebalance];
  }
  [_device unlockforconfiguration];
 }
 
}

根据前后置位置拿到相应的摄像头：

- (avcapturedevice *)camerawithposition:(avcapturedeviceposition)position{
 nsarray *devices = [avcapturedevice deviceswithmediatype:avmediatypevideo];
 for ( avcapturedevice *device in devices )
  if ( device.position == position ){
   return device;
  }
 return nil;
}

3、拍照拿到相应图片：

- (void)photobtndidclick
{
 avcaptureconnection *conntion = [self.imageoutput connectionwithmediatype:avmediatypevideo];
  if (!conntion) {
   nslog(@"拍照失败!");
   return;
   }
 [self.imageoutput capturestillimageasynchronouslyfromconnection:conntion completionhandler:^(cmsamplebufferref imagedatasamplebuffer, nserror *error) {
  if (imagedatasamplebuffer == nil) {
   return ;
   }
  nsdata *imagedata = [avcapturestillimageoutput jpegstillimagensdatarepresentation:imagedatasamplebuffer];
  self.image = [uiimage imagewithdata:imagedata];
  [self.session stoprunning];
  [self.view addsubview:self.cameraimageview];
}

4、保存照片到相册：

#pragma - 保存至相册
- (void)saveimagetophotoalbum:(uiimage*)savedimage
{
 
 uiimagewritetosavedphotosalbum(savedimage, self, @selector(image:didfinishsavingwitherror:contextinfo:), null);
 
}
// 指定回调方法
 
- (void)image: (uiimage *) image didfinishsavingwitherror: (nserror *) error contextinfo: (void *) contextinfo
 
{
 nsstring *msg = nil ;
 if(error != null){
  msg = @"保存图片失败" ;
 }else{
  msg = @"保存图片成功" ;
 }
 uialertview *alert = [[uialertview alloc] initwithtitle:@"保存图片结果提示"
           message:msg
           delegate:self
           cancelbuttontitle:@"确定"
           otherbuttontitles:nil];
 [alert show];
}

5、前后置摄像头的切换

- (void)changecamera{
 nsuinteger cameracount = [[avcapturedevice deviceswithmediatype:avmediatypevideo] count];
 if (cameracount > 1) {
  nserror *error;
  //给摄像头的切换添加翻转动画
  catransition *animation = [catransition animation]；
  animation.duration = .5f；
  animation.timingfunction = [camediatimingfunction functionwithname:kcamediatimingfunctioneaseineaseout];
  animation.type = @"oglflip";
 
  avcapturedevice *newcamera = nil;
  avcapturedeviceinput *newinput = nil;
 //拿到另外一个摄像头位置
  avcapturedeviceposition position = [[_input device] position];
  if (position == avcapturedevicepositionfront){
   newcamera = [self camerawithposition:avcapturedevicepositionback];
   animation.subtype = kcatransitionfromleft;//动画翻转方向
  }
  else {
   newcamera = [self camerawithposition:avcapturedevicepositionfront];
   animation.subtype = kcatransitionfromright;//动画翻转方向
  }
  //生成新的输入
  newinput = [avcapturedeviceinput deviceinputwithdevice:newcamera error:nil];
  [self.previewlayer addanimation:animation forkey:nil];
  if (newinput != nil) {
   [self.session beginconfiguration];
   [self.session removeinput:self.input];
   if ([self.session canaddinput:newinput]) {
    [self.session addinput:newinput];
    self.input = newinput;
 
   } else {
    [self.session addinput:self.input];
   }
   [self.session commitconfiguration];
 
  } else if (error) {
   nslog(@"toggle carema failed, error = %@", error);
  }
 }
}

6、相机的其它参数设置

//avcaptureflashmode 闪光灯
//avcapturefocusmode 对焦
//avcaptureexposuremode 曝光
//avcapturewhitebalancemode 白平衡
//闪光灯和白平衡可以在生成相机时候设置
//曝光要根据对焦点的光线状况而决定,所以和对焦一块写
//point为点击的位置
- (void)focusatpoint:(cgpoint)point{
 cgsize size = self.view.bounds.size;
 cgpoint focuspoint = cgpointmake( point.y /size.height ,1-point.x/size.width );
 nserror *error;
 if ([self.device lockforconfiguration:&error]) {
  //对焦模式和对焦点
  if ([self.device isfocusmodesupported:avcapturefocusmodeautofocus]) {
   [self.device setfocuspointofinterest:focuspoint];
   [self.device setfocusmode:avcapturefocusmodeautofocus];
  }
  //曝光模式和曝光点
  if ([self.device isexposuremodesupported:avcaptureexposuremodeautoexpose ]) {
   [self.device setexposurepointofinterest:focuspoint];
   [self.device setexposuremode:avcaptureexposuremodeautoexpose];
  }
 
  [self.device unlockforconfiguration];
  //设置对焦动画
  _focusview.center = point;
  _focusview.hidden = no;
  [uiview animatewithduration:0.3 animations:^{
   _focusview.transform = cgaffinetransformmakescale(1.25, 1.25);
  }completion:^(bool finished) {
   [uiview animatewithduration:0.5 animations:^{
    _focusview.transform = cgaffinetransformidentity;
   } completion:^(bool finished) {
    _focusview.hidden = yes;
   }];
  }];
 }
 
}

7、遇到的一些坑和解决办法

1) 前后置摄像头的切换

前后值不能切换，各种尝试找了半天没找到有原因。后来发现我在设置图片尺寸的时候设置为1080p [self.session cansetsessionpreset: avcapturesessionpreset1920x1080] ，前置摄像头并不支持这么大的尺寸，所以就不能切换前置摄像头。我验证了下 前置摄像头最高支持720p,720p以内可*切换。　　

当然也可以在前后置摄像头切换的时候，根据前后摄像头来设置不同的尺寸，这里不在赘述。

2）焦点位置

cgpoint focuspoint = cgpointmake( point.y /size.height ,1-point.x/size.width );
setexposurepointofinterest：focuspoint 函数后面point取值范围是取景框左上角（0，0）到取景框右下角（1，1）之间。官方是这么写的：

　　the value of this property is a cgpoint that determines the receiver's focus point of interest, if it has one. a value of (0,0) indicates that the camera should focus on the top left corner of the image, while a value of (1,1) indicates that it should focus on the bottom right. the default value is (0.5,0.5).

我也试了按这个来但位置就是不对，只能按上面的写法才可以。前面是点击位置的y/previewlayer的高度，后面是1-点击位置的x/previewlayer的宽度

3）对焦和曝光

　　我在设置对焦是 先设置了模式setfocusmode，后设置对焦位置，就会导致很奇怪的现象，对焦位置是你上次点击的位置。所以一定要先设置位置，再设置对焦模式。
　　曝光同上

8、写在最后

附上demo：photographdemo

常用到的基本就这么多，写的并不完善，有什么不对的，欢迎大家批评指正，共同学习。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。