UILabel沒有UILabel的更新文本

Question

因此，我不得不承認，這是一個初學者的問題，但是我真的不知道該怎么做，並且花了我幾個小時才能解決。

所以：我的問題是，為什么我要更新其文本時UILabel為nil？

細節：

1：我有兩個視圖，檢測視圖是初始視圖，該視圖的工具欄中有一個UILabel和一個名為“設置”的工具欄按鈕項，第二個視圖是EnterCommandView，其中有一個UITextField和一個條形圖該視圖頂部工具欄中名為“保存”的按鈕項。

2：輸入字符串后，應用程序啟動完成后，單擊“設置”，然后將表單從第一個視圖切換到第二個視圖。 第二，我在UITextField中輸入一些字符串，然后單擊“保存”按鈕，第二個視圖被關閉，然后回到初始視圖，

3： 當我回到InitialView時，剛輸入的字符串應該出現在UILabel中，但是，正確的不是，這正是我的問題，然后我在更新UILabel的位置設置了一個斷點，本文結尾處的信息，表示UILabel為nil

碼：

EnterCommnadViewController.h

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

@protocol EnterCommandDelegate <NSObject>
@optional
-(void) commandEntered:(NSString*)command;
@end
@interface EnterCommandViewController : UIViewController  <RscMgrDelegate,EnterCommandDelegate>
{
RscMgr* rscMgr;
IBOutlet UITextField *inputTextField;
}
-(void)sendMessage:(NSString*)message;
-(id)initWithDelegate:(id)delegateToBe;
- (IBAction)cancelPressed;
- (IBAction)savePressed;
@property (nonatomic,weak) id<EnterCommandDelegate> delegate; 
@end

EnterCommandViewController.m

#import "EnterCommandViewController.h"
#import "DetectionViewController.h"
@interface EnterCommandViewController () <UITextFieldDelegate>
{
@private
BOOL connected;
}
@end
@implementation EnterCommandViewController
@synthesize delegate;

- (void)viewDidLoad {
[super viewDidLoad];
[inputTextField becomeFirstResponder];
}

-(void) viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
inputTextField.delegate = self;
}

-(void) viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
inputTextField.delegate = nil;
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (IBAction)cancelPressed {
[self dismissViewControllerAnimated:YES completion:^{}];
}

- (IBAction)savePressed {
if([[[UIDevice currentDevice]systemVersion] compare:@"7.0"  options:NSNumericSearch] != NSOrderedAscending){
    NSLog(@"SYStem version > 7.0");
}
if(delegate&&[delegate respondsToSelector:@selector(commandEntered:)]){
    [delegate commandEntered:inputTextField.text];
}
[self dismissViewControllerAnimated:YES completion:nil]; //commened: ^{}
}
@end

DetectionViewController.h

#import <UIKit/UIKit.h>
#import "EnterCommandViewController.h"
@interface DetectionViewController : UIViewController <EnterCommandDelegate>{
}
- (IBAction)showSettings:(UIBarButtonItem *)sender;
@property (nonatomic, strong) EnterCommandViewController* enterCVC;
@property (nonatomic, strong) IBOutlet UILabel *showReceivedCommand;
@end

DetectionViewController.m

#import <Foundation/Foundation.h>
#import "DetectionViewController.h"

@implementation DetectionViewController
@synthesize showReceivedCommand;
@synthesize enterCVC;

- (IBAction)showSettings:(UIBarButtonItem *)sender {
}

-(void) viewDidLoad{
    [super viewDidLoad];
}

#pragma mark - EnterCommandDelegate function(s)

-(void)commandEntered:(NSString *)command{
 dispatch_async(dispatch_get_main_queue(), ^{
    showReceivedCommand.text = command;
   });
}
#pragma mark -sugue
-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
 enterCVC = (EnterCommandViewController*)segue.destinationViewController;
[enterCVC setDelegate:self];
}

@end

以下是我設置BreakPoint AT DetectionViewController.m時得到的結果-> -（void） commmandEntered ：（NSString *）command {} -> showReceivedCommand.text = command;

self    DetectionViewController *   0x1465132a0 0x00000001465132a0
command NSString *  @"testStringJustEntered"    0x000000017424ada0
showReceivedCommand UILabel *   0x1465149d0 0x00000001465149d0
UIView  UIView      
UIResponder UIResponder     
_layer  CALayer *   0x17409ae50 0x000000017409ae50
_gestureInfo    id  0x0 0x0000000000000000
_gestureRecognizers NSMutableArray *    nil 0x0000000000000000
_subviewCache   NSArray *   @"0 objects"    0x00000001740033b0
_charge float   0   0
_tag    NSInteger   0   0
_viewDelegate   UIViewController *  nil 0x0000000000000000
_backgroundColorSystemColorName NSString *  nil 0x0000000000000000
_countOfMotionEffectsInSubtree  NSUInteger  0   0
_viewFlags  <anonymous struct>      

Answer 1

UILabel沒錯，我想這是“ commnad”的格式與UILabel中的文本不兼容的問題。

Try follow code for the delegate function:


-(void)commandEntered:(NSString *)command{
dispatch_async(dispatch_get_main_queue(), ^{
    NSString* str1=@"";
    NSString* str=[str1 stringByAppendingString:command];
    showReceivedCommand.text = str;
});
}