EXC_BAD_ACCESS 在 UIPickerView 上 - 我需要一些指导来说明为什么

Question

我在运行我的项目并尝试更改选择器时收到 exc_bad_access 错误。

错误发生在

 - (NSString*)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row
            forComponent:(NSInteger)component

下面是我的代码。通过阅读其他 SO 文章，我意识到我可能没有保留我的变量。我是新手，正在学习并感谢您的帮助。

#import <UIKit/UIKit.h>
#import "RootViewController.h"

@class RootViewController;

@interface AddConditionViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate> {

    IBOutlet UITextField *txtConditionDetail;
    IBOutlet UITextField *txtConditionArea;
    IBOutlet UIPickerView *conditionNamesPicker;
    NSMutableArray *names;
    NSMutableArray *conditionDefs;
    RootViewController *rvc;
    NSString *conditionName;

}

@property (retain, nonatomic) IBOutlet UIPickerView *conditionNamesPicker;
@property (nonatomic,assign) RootViewController *rvc;
@property (nonatomic, retain) NSString *conditionName;
@property (nonatomic,assign) NSMutableArray *names;
@property (nonatomic,assign) NSMutableArray *conditionDefs;

@end


#import "AddConditionViewController.h"
#import "ConditionsAppDelegate.h"
#import "Condition.h"
#import "ConditionDef.h"
#import "Formula.h"

@implementation AddConditionViewController

@synthesize rvc, conditionNamesPicker, names, conditionDefs, conditionName;

/*
// Implement loadView to create a view hierarchy programmatically.
- (void)loadView {
}
*/


// Implement viewDidLoad to do additional setup after loading the view.
- (void)viewDidLoad {
    [super viewDidLoad];

    self.title = @"Add Condition";

    self.navigationItem.leftBarButtonItem = [[[UIBarButtonItem alloc] 
                                              initWithBarButtonSystemItem:UIBarButtonSystemItemCancel 
                                               target:self action:@selector(cancel_Clicked:)] autorelease];

    self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] 
                                               initWithBarButtonSystemItem:UIBarButtonSystemItemSave 
                                               target:self action:@selector(save_Clicked:)] autorelease];

    self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];

    ConditionsAppDelegate *appDelegate = (ConditionsAppDelegate *)[[UIApplication sharedApplication] delegate];

    conditionDefs = appDelegate.getConditionDefs;

    self.names = [NSMutableArray arrayWithCapacity:[conditionDefs count]];

    for (ConditionDef *def in conditionDefs) {
        NSString *condition_name = def.condition_name;

        if (!condition_name) {
            condition_name = @"<Unknown Account>";
        }
        [names addObject:condition_name];
    }

    self.conditionNamesPicker.dataSource = self;
    self.conditionNamesPicker.delegate = self;

    NSLog(@"LINE 48");

 }


- (void) viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    //Set the textboxes to empty string.
    txtConditionArea.text = @"";
    txtConditionDetail.text = @"";

    //Make the Category name textfield to be the first responder.
    [txtConditionArea becomeFirstResponder];

    NSLog(@"LINE 63");

}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview
    // Release anything that's not essential, such as cached data
}

// The number of columns of data
- (int)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 1;
}

// The number of rows of data
- (int)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    NSLog(@" LINE 87 - COUNT OF CONDITION DEFS TO SHOW = %i", names.count);

    [conditionNamesPicker setDataSource:self];

    return [names count];

}

// The data to return for the row and component (column) that's being passed in
- (NSString*)pickerView:(UIPickerView *)pickerView
            titleForRow:(NSInteger)row
           forComponent:(NSInteger)component
{
//    NSLog(@"LINE 94 - here is the bug: conditionDefs[row] %@", names[row]);
    return names[row];
}

// Catpure the picker view selection
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    // This method is triggered whenever the user makes a change to the picker selection.
    // The parameter named row and component represents what was selected.

    conditionName = names[row];

}


- (void) save_Clicked:(id)sender {

    ConditionsAppDelegate *appDelegate = (ConditionsAppDelegate *)[[UIApplication sharedApplication] delegate];

    //Create a Condition Object.
    Condition *c = [[Condition alloc] init];

    NSInteger newId = c.getNextConditionId;

    Condition *cond = [[Condition alloc] initWithPrimaryKey:newId];

    cond.condition_area = txtConditionArea.text;
    cond.condition_detail = txtConditionDetail.text;
    cond.condition_name = conditionName;

    //Add the object
//    [appDelegate addCondition:cond];
    [appDelegate populateFromDatabase];

    // ADD TO THE ARRAY: 
//    [cvc.categories addObject:cond];
//    [cvc.Conditions addObject:cond];

    rvc.Conditions = [appDelegate activeConditions];

    // UPDATE THE TABLEVIEW
    [rvc.tableView reloadData];

    // release
    [cond release];
    [c release];

    //Dismiss the controller.
    [self.navigationController dismissViewControllerAnimated:YES completion: nil];
}

- (void) cancel_Clicked:(id)sender {

    //Dismiss the controller.
    [self.navigationController dismissViewControllerAnimated:YES completion: nil];
}

- (BOOL)textFieldShouldReturn:(UITextField *)theTextField {
    NSLog(@"LINE 159");

    [theTextField resignFirstResponder];
    return YES;
}

- (void)dealloc {
    [txtConditionArea release];
    [txtConditionDetail release];
    [conditionNamesPicker release];
    [super dealloc];
}

@end

Answer 1

您正在DataSource 方法之一中设置PickerView 的数据源。这是无效的。删除下面的行

[conditionNamesPicker setDataSource:self];

来自函数：

numberOfRowsInComponent:

你又在设置了。

Answer 2

请将名称属性的属性 assign 更改为 retain。以及其他数组或那些继承自NSObject的对象。它是一个对象，您将其保留为分配属性。仅对原始数据类型使用赋值。试试这个，让我知道。

EXC_BAD_ACCESS 在 UIPickerView 上 - 我需要一些指导来说明为什么

EXC_BAD_ACCESS on UIPickerView - I need a bit of direction on why

xcode

objective-c

uipickerview

ios