在单个类中的多个方法之间共享NSArray内容

Question

我究竟做错了什么？当我尝试记录数组时,我的代码崩溃了.这是我的班级:

@interface ArrayTestAppDelegate : NSObject <UIApplicationDelegate> {
    UIWindow *window;
    NSArray *array;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) NSArray *array;

-(IBAction)buttonPressed;

@end

@implementation ArrayTestAppDelegate

@synthesize window, array;


- (void)applicationDidFinishLaunching:(UIApplication *)application {    

    array = [NSArray arrayWithObjects:@"Banana", @"Apple", @"Orange", @"Pear", @"Plum", nil];

    [window makeKeyAndVisible];
}

-(IBAction)buttonPressed {

    NSLog(@"%@", array);

}


- (void)dealloc {
    [window release];
    [array release];
    [super dealloc];
}


@end

Answer 1

这是Cocoa中常见的内存管理错误.该类的arrayWithObjects方法NSArray返回一个自动释放的对象.当您尝试在buttonPressed方法中记录数组时,该数组已经被释放并且您将崩溃.修复很简单:

array = [[NSArray alloc] initWithObjects:@"Banana", @"Plum", nil];

要么:

array = [[NSArray arrayWithObjects:@"Banana", @"Plum", nil] retain];

我想第一个更好,第二个例子结束时的保留很容易错过.我建议你在Cocoa中阅读更多关于内存管理的内容.