objective-c - 应用程序因警报 View 而崩溃

Question

我是 Objective C 的新手，我有一个问题。我创建了一个警报 View 并在其中获得了一个文本字段，因此当用户尝试输入名称时，他/她可以将标签命名为他/她为文件名输入的内容。当用户单击“新建”按钮时，会出现一个带有文本框的警报，提示用户输入文件的名称。一旦他们这样做了，说明"new"的按钮将被隐藏，并且说明他们输入的文本的标签将自行取消隐藏。如果他们觉得不再需要该文件，他们可以选择删除它。当他们单击删除按钮时，会出现一个警报，询问他们是否要使用两个按钮删除文件:是和否，但如果他们单击是，则会导致应用程序崩溃。请帮忙。

这是我的头文件:

#import <UIKit/UIKit.h>

NSString *File0Name;
NSString *File1Name;
NSString *File2Name;
NSString *File3Name;

int file;
int delet;

@interface Load : UIViewController <UIAlertViewDelegate>
{
    IBOutlet UIButton *File1;
    IBOutlet UIButton *File2;
    IBOutlet UIButton *File3;

    IBOutlet UIButton *DeleteFile1;
    IBOutlet UIButton *DeleteFile2;
    IBOutlet UIButton *DeleteFile3;

    IBOutlet UILabel *File1Label;
    IBOutlet UILabel *File2Label;
    IBOutlet UILabel *File3Label;

}

-(IBAction)File1:(id)sender;
-(IBAction)File2:(id)sender;
-(IBAction)File3:(id)sender;

-(IBAction)DeleteFile1:(id)sender;
-(IBAction)DeleteFile2:(id)sender;
-(IBAction)DeleteFile3:(id)sender;

@end

这是我的实现文件:

-(IBAction)DeleteFile1:(id)sender{
    NSString *delete1 = [NSString stringWithFormat:@"Are you sure you would like to   delete %@", File1Name];
   UIAlertView *Delete1 = [[UIAlertView alloc] initWithTitle:@"Delete File"  message:delete1 delegate:self cancelButtonTitle:@"Yes" otherButtonTitles:@"No", nil];
  [Delete1 show];

  delet = 1; //This is sortive like a tag so when I specify which button was clicked I can also specify which alert it is for

}

-(IBAction)DeleteFile2:(id)sender{
    NSString *delete2 = [NSString stringWithFormat:@"Are you sure you would like to    delete %@", File2Name];
    UIAlertView *Delete2 = [[UIAlertView alloc] initWithTitle:@"Delete File" message:delete2 delegate:self cancelButtonTitle:@"Yes" otherButtonTitles:@"No", nil];
    [Delete2 show];

    delet = 2; //This is sortive like a tag so when I specify which button was clicked I can also specify which alert it is for

}

-(IBAction)DeleteFile3:(id)sender{
    NSString *delete3 = [NSString stringWithFormat:@"Are you sure you would like to delete %@", File3Name];
    UIAlertView *Delete3 = [[UIAlertView alloc] initWithTitle:@"Delete File" message:delete3 delegate:self cancelButtonTitle:@"Yes" otherButtonTitles:@"No", nil];
    [Delete3 show];

    delet = 3; //This is like a tag so when I specify which button was clicked I can also specify which alert it is for
}

-(IBAction)File1:(id)sender{
UIAlertView *Alert1 = [[UIAlertView alloc] initWithTitle:@"Name this file!" message:@"Enter a name for this new file." delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:@"Cancel", nil];
Alert1.alertViewStyle = UIAlertViewStylePlainTextInput;
[Alert1 show];

file = 1; //This is also like a tag so when I specify which button was clicked I can   also specify which alert it is for

}

-(IBAction)File2:(id)sender{
UIAlertView *Alert2 = [[UIAlertView alloc] initWithTitle:@"Name this file!" message:@"Enter a name for this new file." delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:@"Cancel", nil];
Alert2.alertViewStyle = UIAlertViewStylePlainTextInput;
[Alert2 show];

    file = 2; //This is also like a tag so when I specify which button was clicked I can also specify which alert it is for
}

-(IBAction)File3:(id)sender{
    UIAlertView *Alert3 = [[UIAlertView alloc] initWithTitle:@"Name this file!"   message:@"Enter a name for this new file." delegate:self cancelButtonTitle:@"Ok"  otherButtonTitles:@"Cancel", nil];
    Alert3.alertViewStyle = UIAlertViewStylePlainTextInput;
   [Alert3 show];

   file = 3; //This is also like a tag so when I specify which button was clicked I can also specify which alert it is for
  }

 -(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:    (NSInteger)buttonIndex{

    if ((buttonIndex == 0) && (file == 1)) {
        File1Name = [[alertView textFieldAtIndex:0] text];
        File1Label.text = File1Name;
        File1.hidden = YES;
        File1Label.hidden = NO;
        DeleteFile1.hidden = NO;
        NSLog(@"%@", File1Label.text);

    }

    if ((buttonIndex == 0) && (file == 2)) {
        File2Name = [[alertView textFieldAtIndex:0] text];
        File2Label.text = File2Name;
        File2.hidden = YES;
        File2Label.hidden = NO;
        DeleteFile2.hidden = NO;
        NSLog(@"%@", File2Label.text);

    }

    if ((buttonIndex == 0) && (file == 3)) {
        File3Name = [[alertView textFieldAtIndex:0] text];
        File3Label.text = File3Name;
        File3.hidden = YES;
        File3Label.hidden = NO;
        DeleteFile3.hidden = NO;
        NSLog(@"%@", File3Label.text);
    }

    if ((buttonIndex == 0) && (file == 1)) {
        File1Name = [[alertView textFieldAtIndex:0] text];
        File1Label.text = File1Name;
        File1.hidden = YES;
        File1Label.hidden = NO;
        DeleteFile1.hidden = NO;
        NSLog(@"%i", File1.hidden);
        NSLog(@"%i", File1Label.hidden);
    }

    if ((buttonIndex == 0) && (delet == 1)) {
        File1Label.hidden = YES;
        File1Label.text = @"Label";
        File1.hidden = NO;
        DeleteFile1.hidden = YES;
    }

   if ((buttonIndex == 0) && (delet == 2)) {
       File2Label.hidden = YES;
       File2Label.text = @"Label";
       File2.hidden = NO;
       DeleteFile2.hidden = YES;
   }

   if ((buttonIndex == 0) && (delet == 3)) {
      File3Label.hidden = YES;
      File3Label.text = @"Label";
      File3.hidden = NO;
      DeleteFile3.hidden = YES;
   }

}

- (void)viewDidLoad
{
    DeleteFile1.hidden = YES;
    DeleteFile2.hidden = YES;
    DeleteFile3.hidden = YES;

    File1.hidden = NO;
    File1Label.hidden = YES;

    File2.hidden = NO;
    File2Label.hidden = YES;

   File3.hidden = NO;
   File3Label.hidden = YES;
  [super viewDidLoad];
  // Do any additional setup after loading the view.
}

@end

以防你想知道我在这里取出了“确实收到内存警告”之类的其他方法，所以这不会那么长，但在我真正的 .m 文件中我有它们。

如果这有帮助，以下是调试器控制台中显示的内容:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason:       'textFieldIndex (0) is outside of the bounds of the array of text fields'
*** First throw call stack:
(
0   CoreFoundation                      0x0185b1e4 __exceptionPreprocess + 180
1   libobjc.A.dylib                     0x015da8e5 objc_exception_throw + 44
2   CoreFoundation                      0x0185afbb +[NSException raise:format:] + 139
3   UIKit                               0x007af61d -[UIAlertView textFieldAtIndex:] + 97
4   Balloon Assault                     0x00003700 -[Load alertView:clickedButtonAtIndex:] + 144
5   UIKit                               0x007a9733 -[UIAlertView modalItem:tappedButtonAtIndex:] + 67
6   UIKit                               0x0087bac5 -[_UIModalItemsCoordinator _notifyDelegateModalItem:tappedButtonAtIndex:] + 180
7   UIKit                               0x003b01c8 -[_UIModalItemAlertContentView tableView:didSelectRowAtIndexPath:] + 1035
8   UIKit                               0x003849a1 -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1513
9   UIKit                               0x00384b14 -[UITableView _userSelectRowAtPendingSelectionIndexPath:] + 279
10  UIKit                               0x0038910e __38-[UITableView touchesEnded:withEvent:]_block_invoke + 43
11  UIKit                               0x002b80aa ___afterCACommitHandler_block_invoke + 15
12  UIKit                               0x002b8055 _applyBlockToCFArrayCopiedToStack + 403
13  UIKit                               0x002b7e76 _afterCACommitHandler + 532
14  CoreFoundation                      0x0182336e      __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
15  CoreFoundation                      0x018232bf __CFRunLoopDoObservers + 399
16  CoreFoundation                      0x01801254 __CFRunLoopRun + 1076
17  CoreFoundation                      0x018009d3 CFRunLoopRunSpecific + 467
18  CoreFoundation                      0x018007eb CFRunLoopRunInMode + 123
19  GraphicsServices                    0x0218e5ee GSEventRunModal + 192
20  GraphicsServices                    0x0218e42b GSEventRun + 104
21  UIKit                               0x0029af9b UIApplicationMain + 1225
22  Balloon Assault                     0x0000488d main + 141
23  libdyld.dylib                       0x0268e701 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

你正在崩溃，因为你在说，例如，

File1Name = [[alertView textFieldAtIndex:0] text];

但是您的警报 View 没有文本字段。看看你是如何创建警报 View 的。你在说，例如:

[[UIAlertView alloc] initWithTitle:@"Delete File"  message:delete1 delegate:self cancelButtonTitle:@"Yes" otherButtonTitles:@"No", nil];

该警报 View 中没有文本字段，您也没有在其中放置文本字段。对于某些警报 View ，您正在设置 alertViewStyle至 UIAlertViewStylePlainTextInput它确实为您提供了一个文本字段。但对于其他人，你不是。因此，当您的委托(delegate)代码遇到没有警报 View 的警报 View 时，您会崩溃。

显然，您在委托(delegate)方法中决定您正在响应哪些警报 View 的技术不起作用。这并不奇怪，因为您没有同时设置 file和 delet在任何情况下。但无论如何，这是一个糟糕的主意，因为警报 View 是一回事，而位于 Load 对象中的实例变量是另一回事。从一开始，这就是一种不好的区分方式。

您对这项技术的评论说“这就像一个标签”。但它不像标签。标签将属于警报 View (或其中的某些内容)。

区分这是哪个警报 View 的方法是查看有关警报 View 本身的一些信息。例如，询问其 alertViewStyle !这将告诉您它是否有任何文本字段。