iphone 应用程序 : cannot retrieve property from a Custom Singleton

Question

我在我的 iPhone 应用程序中创建了以下单例:

#import "AppManager.h"

static AppManager *sharedAppManager = nil;

@implementation AppManager

@synthesize currentType, listOfTypes;

#pragma mark Singleton Methods
+ (id)sharedManager {
    @synchronized(self) {
        if (sharedAppManager == nil)
            sharedAppManager = [[self alloc] init];
    }
    return sharedAppManager;
 }
- (id)init {
    if (self = [super init]) {
        currentType = @"";
        listOfTypes = [NSArray arrayWithObjects:@"T1", @"T2", @"T3", nil];
    }
    return self;
}
- (void)dealloc {
    // Should never be called, but just here for clarity really.
    [currentType release];
    [listOfTypes release];
    [super dealloc];
}

@end

当我使用它时:

// TEST
AppManager *appManager = [AppManager sharedManager];
NSArray *array = appManager.listOfTypes;
NSLog(@"TYPES:%@", array);

我有一个奇怪的事情...

TYPES:<UIButtonContent: 0x7b8db10 Title = (null), Image = <UIImage: 0x7bad7f0>, Background = (null), TitleColor = UIDeviceWhiteColorSpace 1 1, ShadowColor = UIDeviceWhiteColorSpace 0 0.5>

它在 currentType(NSString 属性)上工作正常，但在 listOfTypes(NSArray)上却不行

Answer 1

您没有保留数组 listOfTypes，因此该数组可能已被释放并指向一些垃圾值。使用以下内容保留数组(如果它是保留/复制的属性)。

self.listOfTypes = [NSArray arrayWithObjects:@"T1", @"T2", @"T3", nil];

您也可以简单地向阵列发送保留消息。

listOfTypes = [[NSArray arrayWithObjects:@"T1", @"T2", @"T3", nil] retain];

或者分配数组。

listOfTypes = [[NSArray alloc] initWithObjects:@"T1", @"T2", @"T3", nil];