使用NSMutableArray的表的奇怪行爲

Question

我使用以下代碼在我的故事板中創建了一個表視圖。

#import "FastestTapViewController.h" 

@interface FastestTapViewController() 


@end 

@implementation FastestTapViewController 
{ 
    NSMutableArray *recipes; 
} 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    // Initialize table data 
    recipes = [NSMutableArray arrayWithObjects:@"Egg Benedict", @"Mushroom Risotto", @"Full Breakfast", @"Hamburger", @"Ham and Egg Sandwich", nil]; 
} 

- (void)didReceiveMemoryWarning 
{ 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    return [recipes count]; 
} 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *simpleTableIdentifier = @"SimpleTableCell"; 

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier]; 

    if (cell == nil) { 
     cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:simpleTableIdentifier]; 
    } 

    cell.textLabel.text = [recipes objectAtIndex:indexPath.row]; 
    cell.imageView.image = [UIImage imageNamed:@"creme_brelee.jpg"]; 

    return cell; 
} 
@end 

但同時向上滾動顯示如下EXEC_BAD_ACCESS錯誤

如果我使用添加對象見下文然後正常工作

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    // Initialize table data 


    NSMutableArray *recipes = [[NSMutableArray alloc] init]; 
    [recipes addObject:@"Egg Benedict"]; 
    [recipes addObject:@"Mushroom Risotto"]; 

    [recipes addObject:@"Full Breakfast"]; 


} 

我能知道如何解決初始化我的NSMutableArray它殺死它？爲什麼它會在滾動時導致這樣的錯誤？採用第二種方法

編輯錯誤：

*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 4 beyond bounds [0 .. 3]' 
*** First throw call stack: 
(
    0 CoreFoundation      0x01c285e4 __exceptionPreprocess + 180 
    1 libobjc.A.dylib      0x019ab8b6 objc_exception_throw + 44 
    2 CoreFoundation      0x01bc94e6 -[__NSArrayM objectAtIndex:] + 246 
    3 TapGame        0x00002ffc -[FastestTapViewController tableView:cellForRowAtIndexPath:] + 268 
    4 UIKit        0x0080861f -[UITableView _createPreparedCellForGlobalRow:withIndexPath:] + 412 
    5 UIKit        0x008086f3 -[UITableView _createPreparedCellForGlobalRow:] + 69 
    6 UIKit        0x007ec774 -[UITableView _updateVisibleCellsNow:] + 2378 
    7 UIKit        0x007ffe95 -[UITableView layoutSubviews] + 213 
    8 UIKit        0x00784267 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 355 
    9 libobjc.A.dylib      0x019bd81f -[NSObject performSelector:withObject:] + 70 
    10 QuartzCore       0x0429a2ea -[CALayer layoutSublayers] + 148 
    11 QuartzCore       0x0428e0d4 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380 
    12 QuartzCore       0x0428df40 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 26 
    13 QuartzCore       0x041f5ae6 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 294 
    14 QuartzCore       0x041f6e71 _ZN2CA11Transaction6commitEv + 393 
    15 QuartzCore       0x042c2aea _ZN2CA7Display11DisplayLink14dispatch_itemsEyyy + 474 
    16 QuartzCore       0x042c2f6b _ZN2CA7Display16TimerDisplayLink8callbackEP16__CFRunLoopTimerPv + 123 
    17 CoreFoundation      0x01be6bd6 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 22 
    18 CoreFoundation      0x01be65bd __CFRunLoopDoTimer + 1181 
    19 CoreFoundation      0x01bce628 __CFRunLoopRun + 1816 
    20 CoreFoundation      0x01bcdac3 CFRunLoopRunSpecific + 467 
    21 CoreFoundation      0x01bcd8db CFRunLoopRunInMode + 123 
    22 GraphicsServices     0x0361b9e2 GSEventRunModal + 192 
    23 GraphicsServices     0x0361b809 GSEventRun + 104 
    24 UIKit        0x00719d3b UIApplicationMain + 1225 
    25 TapGame        0x0000a3e2 main + 130 
    26 libdyld.dylib      0x02167725 start + 0 
) 
libc++abi.dylib: terminating with uncaught exception of type NSException 
Program ended with exit code: 0 

Answer 1

如果你在你的初始化數組作爲

[NSMutableArray arrayWithObjects:@"Egg Benedict", @"Mushroom Risotto", @"Full Breakfast", @"Hamburger", @"Ham and Egg Sandwich", nil]; 

這就像，你聲明你的陣列autorelease。

[[[NSMutableArray alloc] initWithObjects:@"Egg Benedict", @"Mushroom Risotto", @"Full Breakfast", @"Hamburger", @"Ham and Egg Sandwich", nil] autorelease]; 

你不知道在哪一點，array將被釋放。

所以你最好堅持你的第二個解決方案。

否則請嘗試@property申報方式NSMutablearray。

Answer 2

NSMutableArray recipes可能從內存中釋放，並且您試圖再次使用它。

您需要保留recipes：

recipes = [[NSMutableArray alloc] initWithObjects:@"Egg Benedict", @"Mushroom Risotto", @"Full Breakfast", @"Hamburger", @"Ham and Egg Sandwich", nil]; 

使用initWithObjects將直接初始化數組，這樣就不會被自動釋放;您需要在dealloc中包含[recipes release];。

你也可以使用：

return [self.recipes count]; 

或者乾脆：

[self.recipes count];