Question

我的iPhone应用程序非常简单，但它出错了。我的app delegate打开了这个视图控制器：

#import "Launch.h"

@implementation Launch

- (void)didReceiveMemoryWarning
{
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad {
    [super viewDidLoad];

    self.view.backgroundColor = [UIColor redColor];

    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(100, 100, 100, 100);
    [button setTitle:@"Hello" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonPressed) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

-(void)buttonPressed {
    NSLog(@"Button Pressed!");
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)img editingInfo:(NSDictionary *)editInfo {
    //image.image = img;
    [[picker parentViewController] dismissModalViewControllerAnimated:YES];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

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

@end

这只是一个带按钮的红色屏幕。当我单击按钮时，应用程序出错，没有错误消息。为什么呢？

这是我的main.m方法，当程序出错时，它指向“返回”行并指示线程中的EXEC_BAD_ACCESS。

#import <UIKit/UIKit.h>

#import "testAppDelegate.h"

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([testAppDelegate class]));
    }
}

Answer 1

将其更改为：

@selector(buttonPressed:) //add the :

并使用此：

-(IBAction)buttonPressed:(id)sender;

按钮正在请求操作。

Answer 2

目标类已被解除分配，需要保留。

来自Apple文档：

addTarget:action:forControlEvents:

调用此方法时，不会保留目标。

您需要确保保留类实例。

UIButton简单的应用程序 - iPhone应用程序中的错误

2 个答案: