iphone - AVAudioPlayer 类中的错误？

Question

我会保持简短和甜蜜 - 在我为自己购买 iPhone 开发者计划之前，我正在构建一个应用程序只是为了练习。

我正在尝试 AVFoundation.framework，但一直遇到一个错误，该错误只会让我播放在代码中初始化的第一个声音。你认为你们中有人可以帮助我吗？提前致谢!! :)

View Controller

-(IBAction)play {
    if (segments.selectedSegmentIndex == 0) {
        NSLog(@"Segment = 0");
        NSBundle *bundle = [NSBundle mainBundle];
        NSString *path = [bundle pathForResource:@"meow" ofType:@"wav"];

        if (path != nil) {
            NSURL *url = [NSURL fileURLWithPath:path];
            AVAudioPlayer *player = [[AVAudioPlayer alloc]initWithContentsOfURL:url error:NULL];
            [player prepareToPlay];
            [player play];
        }
    }

    else if (segments.selectedSegmentIndex == 1) {
        NSLog(@"Segment = 1");
        NSBundle *bundle = [NSBundle mainBundle];
        NSString *path2 = [bundle pathForResource:@"meowloud" ofType:@"wav"];

        if (path2 != nil) {
            NSURL *url2 = [NSURL fileURLWithPath:path2];
            AVAudioPlayer *player2 = [[AVAudioPlayer alloc]initWithContentsOfURL:url2 error:NULL];
            [player2 prepareToPlay];
            [player2 play];
//          [player2 release];
        }
    }

    text1.textColor = [UIColor clearColor];
    text2.textColor = [UIColor clearColor];
    text3.textColor = [UIColor clearColor];
    text4.textColor = [UIColor clearColor];

}

执行此代码时，无论选择哪个段，都只会执行 meow.wav。

Answer 1

您的代码存在一些内存泄漏。您在 play 方法中分配 AVAudioPlayer 的实例，但永远不会释放这些实例。请参阅Cocoa's memory management qguidelines了解详情。由于 AVAudioPlayer 实例需要保留在内存中才能播放，最简单的解决方案是向 viewController 类添加一个成员变量并将其设置为 retain 属性。

为了Don't Repeat Yourself (DRY) ，我还建议添加一个方法来封装播放单个 wav 文件所需的所有代码。

这是我编写此 View Controller 的方式:

MyViewController.h

@interface MyViewController : UIViewController
{
    AVAudioPlayer *player;
}
@property(nonatomic, retain) AVAudioPlayer *player;
- (void)playWavFile:(NSString *)fileName;
- (IBAction)play;
@end

MyViewController.m

@synthesize player;

- (void)dealloc {
    [player release];
}

- (void)playWavFile:(NSString *)fileName {
    NSBundle *bundle = [NSBundle mainBundle];   
    NSString *path = [bundle pathForResource:fileName ofType:@"wav"];

    if (path != nil) {
        AVAudioPlayer *newPlayer;
        NSURL *url = [NSURL fileURLWithPath:path];
        newPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url
                                                           error:NULL];
        [self setPlayer:newPlayer];
        [newPlayer release];

        [newPlayer prepareToPlay];
        [newPlayer play];
    }
}

- (IBAction)play {

    if (segments.selectedSegmentIndex == 0) {
        [self playWavFile:@"meow"];
    }
    else if (segments.selectedSegmentIndex == 1) {
        [self playWavFile:@"meowloud"];
    }
}