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我想静音铃声音量。所以我使用这个链接来做到这一点 -如何禁用 iOS 系统声音 但是如果我使用代码：

- (void) setSystemVolumeLevelTo:(float)newVolumeLevel
{
    Class avSystemControllerClass = NSClassFromString(@"AVSystemController");
    id avSystemControllerInstance = [avSystemControllerClass performSelector:@selector(sharedAVSystemController)];

NSString *soundCategory = @"Ringtone";

NSInvocation *volumeInvocation = [NSInvocation invocationWithMethodSignature:
                                  [avSystemControllerClass instanceMethodSignatureForSelector:
                                   @selector(setVolumeTo:forCategory:)]];
[volumeInvocation setTarget:avSystemControllerInstance];
[volumeInvocation setSelector:@selector(setVolumeTo:forCategory:)];
[volumeInvocation setArgument:&newVolumeLevel atIndex:2];
[volumeInvocation setArgument:&soundCategory atIndex:3];
[volumeInvocation invoke];

}

它崩溃了

NSInvocation *volumeInvocation = [NSInvocation invocationWithMethodSignature:
                                  [avSystemControllerClass instanceMethodSignatureForSelector:
                                   @selector(setVolumeTo:forCategory:)]];

因为返回的值为零。

如果我导入框架等然后使用此代码

[[AVSystemController sharedAVSystemController] setVolumeTo:0.0 forCategory:@"Ringtone"];

它没有运行给我以下错误：

Undefined symbols for architecture i386:
  "_OBJC_CLASS_$_AVSystemController", referenced from:
  objc-class-ref in SettingsViewController.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

有人请指导我哪里出错了。

4

1 回答 1

2

All you have to do is to add following lines in you first method. As you are using a private framework(Celestial) so you have to import it on runtime.

NSBundle *bundle = [NSBundle bundleWithPath:@"/System/Library/PrivateFrameworks/Celestial.framework"];
BOOL success = [bundle load];
于 2014-07-03T09:32:22.980 回答