使用Parse API在IOS App中将无法识别的选择器发送到实例错误

Question

我正在尝试通过开发一个简单的应用程序来学习Ios应用程序开发，该应用程序从用户那里获取输入并将其使用Parse API保存在云中。

输入字段是firstName和lastName。

该API运作良好，我已经对其进行了测试（对要保存的值进行硬编码，而不是从屏幕上提取出来）。 但是，仅当我尝试从屏幕上获取输入并保存它时，才会出现该错误。

以下是代码：

viewcontroller.h

#import <UIKit/UIKit.h>
#import <Parse/Parse.h>

@interface ViewController : UIViewController    

@property (weak, nonatomic) IBOutlet UITextField *firstName;
@property (weak, nonatomic) IBOutlet UITextField *lastName;

- (IBAction)saveButton:(id)sender;

@end

视图控制器

#import "ViewController.h"
#import <Parse/Parse.h>

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
    //*** Following works as I have hard coded the values to be stored and when I click directly on the save button.  ***//
    //*** But I want to get the content in firstName and lastName and save them using Parse API ***//
-     (IBAction)saveButton:(UIButton *)sender {
    PFObject *testObject = [PFObject objectWithClassName:@"NimbleIOS"];
    testObject[@"FirstName"] = @"frst";// _firstName.text;
    testObject[@"LastName"] = @"lst";// _lastName.text;
    [testObject saveInBackground];
}

@end


error: 

2014-11-19 22:38:45.229 Nimble[11714:541175] -[ViewController firstName:]: unrecognized selector sent to instance 0x7fe568e36160
2014-11-19 22:38:45.234 Nimble[11714:541175] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[ViewController firstName:]: unrecognized selector sent to instance 0x7fe568e36160'
*** First throw call stack:
(
0   CoreFoundation                      0x000000010cd57f35 __exceptionPreprocess + 165
1   libobjc.A.dylib                     0x000000010c9f0bb7 objc_exception_throw + 45
2   CoreFoundation                      0x000000010cd5f04d -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
3   CoreFoundation                      0x000000010ccb727c ___forwarding___ + 988
4   CoreFoundation                      0x000000010ccb6e18 _CF_forwarding_prep_0 + 120
5   UIKit                               0x000000010d1458be -[UIApplication sendAction:to:from:forEvent:] + 75
6   UIKit                               0x000000010d24c410 -[UIControl _sendActionsForEvents:withEvent:] + 467
7   UIKit                               0x000000010d8784cb -[UITextField _resignFirstResponder] + 256
8   UIKit                               0x000000010d2bb47b -[UIResponder resignFirstResponder] + 114
9   UIKit                               0x000000010d8782d4 -[UITextField resignFirstResponder] + 114
10  UIKit                               0x000000010d2bb265 -[UIResponder becomeFirstResponder] + 284
11  UIKit                               0x000000010d1b0e03 -[UIView(Hierarchy) becomeFirstResponder] + 99
12  UIKit                               0x000000010d877ad7 -[UITextField becomeFirstResponder] + 51
13  UIKit                               0x000000010d4ff9c1 -[UITextInteractionAssistant(UITextInteractionAssistant_Internal) setFirstResponderIfNecessary] + 177
14  UIKit                               0x000000010d501a30 -[UITextInteractionAssistant(UITextInteractionAssistant_Internal) oneFingerTap:] + 2263
15  UIKit                               0x000000010d4f72e6 _UIGestureRecognizerSendActions + 262
16  UIKit                               0x000000010d4f5f89 -[UIGestureRecognizer _updateGestureWithEvent:buttonEvent:] + 532
17  UIKit                               0x000000010d4faba6 ___UIGestureRecognizerUpdate_block_invoke662 + 51
18  UIKit                               0x000000010d4faaa2 _UIGestureRecognizerRemoveObjectsFromArrayAndApplyBlocks + 254
19  UIKit                               0x000000010d4f0b1d _UIGestureRecognizerUpdate + 2796
20  UIKit                               0x000000010d18aff6 -[UIWindow _sendGesturesForEvent:] + 1041
21  UIKit                               0x000000010d18bc23 -[UIWindow sendEvent:] + 667
22  UIKit                               0x000000010d1589b1 -[UIApplication sendEvent:] + 246
23  UIKit                               0x000000010d165a7d _UIApplicationHandleEventFromQueueEvent + 17370
24  UIKit                               0x000000010d141103 _UIApplicationHandleEventQueue + 1961
25  CoreFoundation                      0x000000010cc8d551 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
26  CoreFoundation                      0x000000010cc8341d __CFRunLoopDoSources0 + 269
27  CoreFoundation                      0x000000010cc82a54 __CFRunLoopRun + 868
28  CoreFoundation                      0x000000010cc82486 CFRunLoopRunSpecific + 470
29  GraphicsServices                    0x00000001102429f0 GSEventRunModal + 161
30  UIKit                               0x000000010d144420 UIApplicationMain + 1282
31  Nimble                              0x000000010b545d43 main + 115
32  libdyld.dylib                       0x000000010ea1c145 start + 1
33  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

有人可以帮助我知道我犯的错误吗？ 我已经引用了两个文本字段以及从主板到视图控制器的保存按钮。 在文本字段中输入文本并将其移开（EditingDidEnd）并触摸屏幕上的其他位置后，出现错误。

Answer 1

firstName：方法在哪里？ 我只看到一个名为saveButton的IBAction方法：即：saveButton是@selector（）而不是firstName：我认为您需要在接口生成器中查看您的网点，看看是否仍然有一个旧的网点仍被连接为firstName：匹配字符串文字“ FirstName”

我没有使用PFObject类

我想你虽然在尝试做这样的事情

-(IBAction)saveButton:(UIButton *)sender{
    if([sender.restorationIdentifier isEqualToString: @"res string from IB"]){
    ...take string from input source as a string and use it
    maybe grab something from a textField or whatever
    }else if...

}

您也可能要确保发件人实际上是一个UIButton，我看到您的公共api中列出了ID，而我刚读完底部，它说您要留下一个不是UIButton实例的textField！

Answer 2

我不小心在发送的事件中添加了“ EditingDidEnd”。 该代码期望在文本字段中编辑结束后立即发生。 该代码现在可以正常工作。 （在尝试使代码正常工作时，我已经写了我所理解的东西。如果我的理解是错误的，请更正我：））