有關的NSString

Question

的問題是在我按2個按鈕的應用程序崩潰，我想不通爲什麼

Button1的是連接到Button1的 Button2的是有線BUTTON2 一個重要的問題... Button5是有線to button5

我在做什麼錯？

基本上我想檢查，如果排名的順序正確地（55235）

在我AppDelegate.H文件被打孔，我已經定義了一個名爲

的NSString * myEasterEgg變量;

在AppDelegate.M，我有5個按鈕，接線正確，並且每個按鈕都有它自己的方法

-(IBAction)button1:(id)sender 
{ 
if(CFStringCompare((CFStringRef)myEasterEgg, (CFStringRef)@"52235", 1) == 0) 
{ 
myEasterEgg = @""; 
} else { 
myEasterEgg = [myEasterEgg stringByAppendingString:@"1"]; 
} 
} 

-(IBAction)button2:(id)sender 
{ 
if(CFStringCompare((CFStringRef)myEasterEgg, (CFStringRef)@"52235", 1) == 0) 
{ 
myEasterEgg = @""; 
} else { 
myEasterEgg = [myEasterEgg stringByAppendingString:@"2"]; 
} 
} 

-(IBAction)button3:(id)sender 
{ 
if(CFStringCompare((CFStringRef)myEasterEgg, (CFStringRef)@"52235", 1) == 0) 
{ 
myEasterEgg = @""; 
} else { 
myEasterEgg = [myEasterEgg stringByAppendingString:@"3"]; 
} 
} 

-(IBAction)button4:(id)sender 
{ 
if(CFStringCompare((CFStringRef)myEasterEgg, (CFStringRef)@"52235", 1) == 0) 
{ 
myEasterEgg = @""; 
} else { 
myEasterEgg = [myEasterEgg stringByAppendingString:@"4"]; 
} 
} 

-(IBAction)button5:(id)sender 
{ 
if(CFStringCompare((CFStringRef)myEasterEgg, (CFStringRef)@"52235", 1) == 0) 
{ 
myEasterEgg = @""; 
} else { 
myEasterEgg = [myEasterEgg stringByAppendingString:@"5"]; 
} 
} 

-(void)viewDidLoad 
{ 
myEasterEgg = [[NSString alloc] initWithString:@""]; 
} 

Answer 1

你泄露你的原始字符串，並用新值替換它沒有留住他們。發生崩潰是因爲你在懸掛指針上調用[myEasterEgg stringByAppendingString:…]，即一個不再引用任何對象的變量。有關更多信息，請參閱Memory Management Programming Guide。