Question

有一个initWithCoder方法调用两个属性（文本，已选中），但由于某种原因，无法看到它们。已注释错误消息。

ChecklistViewController.m

#import "ChecklistsViewController.h"
#import "ChecklistItem.h"

@interface ChecklistsViewController ()

@end

@implementation ChecklistsViewController {

    NSMutableArray *_items;
}
-(NSString *)documentsDirectory
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths firstObject];
    return documentsDirectory;
}

-(NSString *)dataFilePath
{
    return [[self documentsDirectory] stringByAppendingPathComponent:@"Checklists.plist"];
}

-(void)saveChecklistItems
{
    NSMutableData *data = [[NSMutableData alloc] init];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
    [archiver encodeObject:_items forKey:@"ChecklistItems"];
    [archiver finishEncoding];
    [data writeToFile:[self dataFilePath] atomically:YES];
}

-(void)loadChecklistItems
{
    NSString *path = [self dataFilePath];
    if ([[NSFileManager defaultManager]fileExistsAtPath:path]) {
        NSData *data = [[NSData alloc] initWithContentsOfFile:path];
        NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];

        _items = [unarchiver decodeObjectForKey:@"ChecklistItems"];
        [unarchiver finishDecoding];
    } else {
        _items = [[NSMutableArray alloc] initWithCapacity:20];
    }
}

-(id)initWithCoder:(NSCoder *)aDecoder
{
    if ((self = [super init])) {
        self.text = [aDecoder decodeObjectForKey:@"Text"]; //Property 'text' not found on 'ChecklistsViewController'
        self.checked = [aDecoder decodeBoolForKey:@"Checked"]; //Property 'checked' not found on 'ChecklistsViewController'
    }
    return self;
}

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

}

ChecklistItem.h

#import <Foundation/Foundation.h>

@interface ChecklistItem : NSObject <NSCoding>

@property (nonatomic, copy) NSString *text;
@property (nonatomic, assign) BOOL checked;

-(void)toggleChecked;

@end

Answer 1

您的initWithCoder:方法位于名为ChecklistsViewController的类中，self引用ChecklistsViewController实例。但text和checked属性是ChecklistItem类的成员。

initWithCoder无法在ChecklistItem.h中看到声明的属性

1 个答案: