Objective c NSTask在xCode中启动问题

我正试图使用此代码在应用程序包中获取ImageMagick库，但这非常复杂：

-(id)init
{
    if ([super init])
    {
        NSString* bundlePath = [[NSBundle mainBundle] bundlePath];
        NSString* imageMagickPath = [bundlePath stringByAppendingPathComponent:@"/Contents/Resources/ImageMagick"];
        NSString* imageMagickLibraryPath = [imageMagickPath stringByAppendingPathComponent:@"/lib"];

        MAGICK_HOME = imageMagickPath;
        DYLD_LIBRARY_PATH = imageMagickLibraryPath;
    }
    return self;
}

-(void)composite
{
    NSTask *task = [[NSTask alloc] init];

    // the ImageMagick library needs these two environment variables.
    NSMutableDictionary* environment = [[NSMutableDictionary alloc] init];
    [environment setValue:MAGICK_HOME forKey:@"MAGICK_HOME"];
    [environment setValue:DYLD_LIBRARY_PATH forKey:@"DYLD_LIBRARY_PATH"];

    // helper function from
    // http://www.karelia.com/cocoa_legacy/Foundation_Categories/NSFileManager__Get_.m
    NSString* pwd = [Helpers pathFromUserLibraryPath:@"MyApp"];

    // executable binary path
    NSString* exe = [MAGICK_HOME stringByAppendingPathComponent:@"/bin/composite"];

    [task setEnvironment:environment];
    [task setCurrentDirectoryPath:pwd]; // pwd
    [task setLaunchPath:exe]; // the path to composite binary
    // these are just example arguments
    [task setArguments:[NSArray arrayWithObjects: @"-gravity", @"center", @"stupid hat.png", @"IDR663.gif", @"bla.png", nil]];
    [task launch];
    [task waitUntilExit];
}

DYLD\u LIBRARY\u路径

和

MAGICK\u HOME

标识符的声明（已解决）

更新： 但当我尝试构建并运行它时，我的应用程序崩溃了。崩溃时间：

[任务启动]

控制台消息：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'working directory doesn't exist.'

我如何解决当前的问题

更新2：
当前代码：

- (id)initWithCoder:(NSCoder *)coder
{
NSString* bundlePath = [[NSBundle mainBundle] bundlePath];
NSString* imageMagickPath = [bundlePath stringByAppendingPathComponent:@"/Contents/Resources/ImageMagick"];
NSString* imageMagickLibraryPath = [imageMagickPath stringByAppendingPathComponent:@"/lib"];

MAGICK_HOME = imageMagickPath;
DYLD_LIBRARY_PATH = imageMagickLibraryPath;
[self composite];
}

-(void)composite
{
    NSTask *task = [[NSTask alloc] init];
    
    NSMutableDictionary* environment = [[NSMutableDictionary alloc] init];
    [environment setValue:MAGICK_HOME forKey:@"MAGICK_HOME"];
    [environment setValue:DYLD_LIBRARY_PATH forKey:@"DYLD_LIBRARY_PATH"];
    
    NSString* loc = [[NSString stringWithFormat:@"%@", MAGICK_HOME] retain];
    NSString* exe = MAGICK_HOME;
    
    [task setEnvironment:environment];
    NSString* pwd = @"/opt/local/lib/";
    [task setCurrentDirectoryPath:pwd];
    [task setLaunchPath:loc];
    NSLog(@"%@", loc);
    NSLog(@"%@", pwd);
    [task setArguments:[NSArray arrayWithObjects: @"-gravity", @"center", @"stupid hat.png", @"IDR663.gif", @"bla.png", nil]];
    [task launch];
    [task waitUntilExit];
}

和当前错误（在控制台中）：

必须使用可执行二进制文件的路径调用
[task setLaunchPath:…]
。在“更新2”代码中，您使用目录路径调用它
 
NSString*MAGICK\u HOME，*DYLD\u LIBRARY\u PATH
@Julius:你在哪里声明MAGICK\u HOME，DYLD\u LIBRARY\u PATH？请显示您的更新代码。检查
pwd
是否真的包含预期的路径，无论是在调试器中还是在
NSLog（@“pwd=%@”，pwd）
之前
[任务启动]
。好的，我只需要一点时间来下载新的xCode，因为山狮更新了操作系统，我现在不能使用旧的xCode，所以我无法打开我的项目。用当前代码更新了问题，并在更改目录位置后遇到另一个错误
*** NSTask: Task create for path '/Users/development/Library/Developer/Xcode/DerivedData/OGL-cahltqazoqxhrthkxztsqyvvodge/Build/Products/Debug/OGL.app/Contents/Resources/ImageMagick' failed: 22, "Invalid argument".  Terminating temporary process.