ios - NSString 属性在其他方法中的 init 方法后为空？

Question

我有一个小问题。这是我的源代码:

.h:

#import <UIKit/UIKit.h>

@interface TBNoteViewController : UIViewController <UITextViewDelegate>
@property (nonatomic, copy) NSString *noteKey;
- (IBAction)dismissKeyboard:(id)sender;
- (id)initWithNoteIndex:(int)index;
@end

他们:

#import "TBNoteViewController.h"
#import "PSPDFTextView.h"
#include <tgmath.h>

@interface TBNoteViewController ()
{
CGRect _keyboardRect;
BOOL _keyboardVisible;
}

@property (nonatomic, strong) UIBarButtonItem *rightBarButton;
@property (nonatomic, strong) PSPDFTextView *textView;

@end

@implementation TBNoteViewController
@synthesize noteKey;

- (id)initWithNoteIndex:(int)index
{
self = [super init];

if (self) {
    NSMutableArray *data = [[NSMutableArray alloc] initWithArray:[[NSUserDefaults   standardUserDefaults] objectForKey:@"Notes"] copyItems:YES];
    self.noteKey = [NSString stringWithFormat:@"%@", [data objectAtIndex:index]];

    NSLog(@"1: %@", self.noteKey);
}

return self;
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
    // Custom initialization
}
return self;
}

- (void)viewDidLoad
{

NSLog(@"2: %@", self.noteKey);

// Register notifications
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShowNotification:) name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHideNotification:) name:UIKeyboardWillHideNotification object:nil];

_rightBarButton = [self.navigationItem rightBarButtonItem];

self.navigationItem.rightBarButtonItem = nil;

PSPDFTextView *textView = [[PSPDFTextView alloc] initWithFrame:self.view.bounds];
textView.delegate = self;
textView.autoresizingMask = UIViewAutoresizingFlexibleHeight|UIViewAutoresizingFlexibleWidth;
textView.font = [UIFont systemFontOfSize:17.f];

[self.view addSubview:textView];

self.textView = textView;

[self.textView setTextContainerInset:UIEdgeInsetsMake(5, 12, 5, 12)];
self.textView.alwaysBounceVertical = YES;
self.textView.keyboardAppearance = UIKeyboardAppearanceDark;

textView.text = self.noteKey;

[super viewDidLoad];
// Do any additional setup after loading the view.
}

所以我的问题是属性 noteKey 有一个字符串，但在 viewDidLoad 中它是空的。

所以，你可以看到 NSLogs，输出将是(只是复制那个):

2014-02-13 23:07:21.197 TaskBeater [3205:70b] 1:呵呵。

2014-02-13 23:07:21.199 TaskBeater [3205:70b] 2: (null)

如果您能帮助我，我将不胜感激，我不知道那里出了什么问题。

Answer 1

在我看来，您正在实例化两个不同的“TBNoteViewController”实例。

您正在以编程方式(在代码中)执行一项操作，这就是您如何让“noteKey”属性正确显示。

然后创建第二个，因为您从 XIB 文件加载它，这就是调用“viewDidLoad:”的原因。

在去掉你在代码中调用的额外的那个之后，为你通过 XIB 文件创建的那个创建一个导出，然后你可以在上面设置属性，你应该已经准备好了。