預期的標識符錯誤

Question

因此，如果有人可以幫助我，我只會在- (IBAction)playAudio:(id)sender下收到一個錯誤，我將只在按下按鈕時嘗試播放聲音。

#import "SecondViewController.h"

@interface SecondViewController ()

- (IBAction)playAudio:(id)sender {
    AVAudioPlayer *audioPlayer;
    NSString *audioPath = [[NSBundle mainBundle] pathForResource:@"ding" ofType:@"wav"];
    NSURL *audioPath = [NSURL fileURLWithPath:audioPath];
    audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:audioURL error:nil];
    [audioPlayer play];
}

@end

@implementation SecondViewController{

}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (IBAction)ButtonPressed:(UIButton *)sender forEvent:(UIEvent *)event {
}

- (IBAction)Button {AudioServicesPlaySystemSound(soundID);
}

- (IBAction)playAudio:(id)sender {
}

@end

Answer 1

方法定義不應在@interface部分中； 只是聲明 ：

@interface SecondViewController ()

- (IBAction)playAudio:(id)sender;

@end

然后通過以下更改將定義移至@implementation部分：

您將標識符（變量名） audioPath兩次用於不同的對象。 將第二個更改為audioURL或諸如此類：

- (IBAction)playAudio:(id)sender {
    AVAudioPlayer *audioPlayer;
    NSString *audioPath = [[NSBundle mainBundle] pathForResource:@"ding" ofType:@"wav"];
    NSURL *audioURL = [NSURL fileURLWithPath:audioPath];   // HERE
    audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:audioURL error:nil];
    [audioPlayer play];
}

Answer 2

您是否要在頭文件（.h）中實現（IBAction）playAudio：（id）sender {}？

您可以在.h中聲明playAudio IBAction，但在.m中實現它

您的文件應如下所示：

@interface SecondViewController ()

- (IBAction)playAudio:(id)sender;

@end

@implementation SecondViewController{

}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (IBAction)ButtonPressed:(UIButton *)sender forEvent:(UIEvent *)event {
}

- (IBAction)Button {AudioServicesPlaySystemSound(soundID);
}

- (IBAction)playAudio:(id)sender {
    AVAudioPlayer *audioPlayer;
    NSString *audioPath = [[NSBundle mainBundle] pathForResource:@"ding" ofType:@"wav"];
    NSURL *audioPath = [NSURL fileURLWithPath:audioPath];
    audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:audioURL error:nil];
    [audioPlayer play];
}

@end