在ios应用中，我们经常会碰到一些基于ios多媒体的开发使用。
本篇文章中简单介绍一下三个知识点：
1.图片的采集和显示
2.音频的录制和播放
3.视频的录制和播放
首先，我们来看一张框架图，基本了解一下在ios中关于多媒体开发的底层框架的概念。
多媒体.png
一、图片的采集和显示
1.布置UI部分（UIButton 和 UIImageView）
2.导入关于图片操作的框架
#import
#import
#import
3.创建UIImagePickerController对象，声明代理
-(UIImagePickerController *)imagePicker
{
if (!_imagePicker) {
_imagePicker = [[UIImagePickerController alloc]init];
// 采集源类型
_imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
// 媒体类型 #import
_imagePicker.mediaTypes = [NSArray arrayWithObject:(__bridge NSString*)(kUTTypeImage)];
// _imagePicker.videoQuality = UIImagePickerControllerQualityTypeHigh; //视频质量
_imagePicker.delegate = self;
}
return _imagePicker;
}
4.根据数据来源，设置图片采集来源，进行图片采集
- (IBAction)selectImage:(id)sender {
// 通过摄像头采集
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
self.imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
}
else // 通过图片库来采集
{
self.imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
}
[self presentViewController:self.imagePicker animated:YES completion:nil];
}
5.图片的显示，实现UIImagePickerDelegate的代理方法，完成图片的选择显示和取消回调
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
// 获取媒体类型
NSString * type =info[UIImagePickerControllerMediaType];
// 如果媒体类型是图片类型
if ([type isEqualToString:(__bridge NSString*)(kUTTypeImage)]) {
UIImage * image = info[UIImagePickerControllerOriginalImage];
self.imageView.image = image;
}
[self dismissViewControllerAnimated:YES completion:nil];
}
// 取消采集图片的处理
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
[self dismissViewControllerAnimated:YES completion:nil];
}
二、音频的录制和播放
开发之前的注意事项：
如果是播放本地音频文件的情况需要保证音频文件处在target编译目录下，图示：
bug.png
如果音频文件没有在编译目录下，音频播放时会找不到文件路径，程序崩溃，出现以下错误日志
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter’
1.1.布置UI部分（UIButton）
2.导入关于图片操作的框架(同上)
#import
#import
#import
3.创建AVAudioRecorder(录音)和AVAudioRecorder(播放)对象。
// 录音
@property (nonatomic,strong) AVAudioRecorder * recorder;
@property (nonatomic,strong) AVAudioPlayer * audioPlayer;
-(AVAudioPlayer *)audioPlayer
{
if (!_audioPlayer) {
//如果是录音文件，则在播放的时候把录音文件存入的文件路径拿到
// NSString * path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/record"];
// 播放本地文件
NSString * path = [[NSBundle mainBundle] pathForResource:@"黎允文 - 赵子龙" ofType:@"mp3"];
_audioPlayer = [[AVAudioPlayer alloc]initWithContentsOfURL:[NSURL fileURLWithPath:path] error:nil];// 创建播放机对象
[_audioPlayer prepareToPlay]; // 准备播放
}
return _audioPlayer;
}
- (AVAudioRecorder *)recorder
{
if (!_recorder) {
// 录音保存路径
NSString * path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/record"];
// 录音设置
NSMutableDictionary * dic = [[NSMutableDictionary alloc]init];
//采样率
[dic setValue:@(44100) forKey:AVSampleRateKey];
//录音格式
[dic setValue:[NSNumber numberWithInt:kAudioFormatMPEG4AAC] forKey:AVFormatIDKey];
//录音通道
[dic setValue:@(1) forKey:AVNumberOfChannelsKey];
// 录音质量
[dic setValue:[NSNumber numberWithInt:AVAudioQualityHigh] forKey:AVEncoderAudioQualityKey];
//
_recorder = [[AVAudioRecorder alloc]initWithURL:[NSURL URLWithString:path] settings:dic error:nil];
[_recorder prepareToRecord]; //准备录音
}
return _recorder;
}
4.录音按钮的设置
- (IBAction)pickVideo:(UIButton*)sender {
if (sender.isSelected ==NO) {
[self.recorder record];
sender.selected = YES;
}
else
{
[self.recorder stop];
sender.selected = NO;
}
}
5.开始播放
- (IBAction)playMedia:(id)sender {
// 播放
[self.audioPlayer play];
}
三、视频的录制和播放
基本步骤
1.视频文件路径
2.播放窗口大小的设置 全屏/小屏幕
3.播放视频文件
1.布置UI部分（UIButton）
2.导入关于图片操作的框架(同上)
#import
#import
#import
3.创建视频选择对象和视频播放对象，实现协议
{
NSURL * mediaUrl;
}
@property(nonatomic,strong)UIImagePickerController * imagePicker;
@property (nonatomic,strong)AVPlayerViewController * avPlayer;
创建对象
- (AVPlayerViewController *)avPlayer
{
if (!_avPlayer) {
_avPlayer = [[AVPlayerViewController alloc]init];
//创建Player对象 -- 视频文件路径
_avPlayer.player = [[AVPlayer alloc]initWithURL:mediaUrl];
// 播放窗口大小
self.avPlayer.view.frame = CGRectMake(100, 100, 400, 400);
[self.view addSubview:self.avPlayer.view];
//1.全屏播放
[self presentViewController:self.avPlayer animated:YES completion:nil];
}
return _avPlayer;
}
-(UIImagePickerController *)imagePicker
{
if (!_imagePicker) {
_imagePicker = [[UIImagePickerController alloc]init];
_imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
_imagePicker.mediaTypes = [NSArray arrayWithObject:(__bridge NSString*)(kUTTypeMovie)];
_imagePicker.videoQuality = UIImagePickerControllerQualityTypeHigh; //视频质量
_imagePicker.delegate = self;
}
return _imagePicker;
}
4.采集和播放视频，完成回调操作
1.采集视频
- (IBAction)pickVideo:(id)sender {
// 如果摄像头可用，从摄像头采集视频数据
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
[self presentViewController:self.imagePicker animated:YES completion:nil];
}
}
2.回调处理
// 采集媒体数据完成的回调处理
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
// 获取媒体类型
NSString * type =info[UIImagePickerControllerMediaType];
if ([type isEqualToString:(__bridge NSString*)(kUTTypeMovie)]) {
// 获取视频媒体的url
mediaUrl = info[UIImagePickerControllerMediaURL];
}
[self dismissViewControllerAnimated:YES completion:nil];
}
// 采集媒体数据取消的回调处理
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
// 取消采集视频
[self dismissViewControllerAnimated:YES completion:nil];
}
3.视频播放
- (IBAction)playMedia:(id)sender {
// 播放视频
[self.avPlayer.player play];
}
ios开发中，为方便优化内存，以上创建对象时，均使用懒加载方式。
至此，ios多媒体的简单开发介绍到这里。
END