Ios alloc和Init的失败

所以，也许这是一个初学者的错误，对你们来说非常容易，但我真的不知道如何解决它，非常感谢你们的建议： 现在：

1:我必须查看控制器：输入CommandViewController和DetectionViewController

2：我在EnterCommandViewController中编写了委托协议，并将DetectionViewController设置为其委托

3：关于代理：我在EnterCommandView中有一个InputExtField，在该视图的顶部工具栏上有一个“保存”栏按钮项。单击保存后，当前视图将被取消并返回到DetectionView，并在DetectionView中显示刚刚在UILabel中输入的NSString

最后，我的问题是，为什么在我分配并初始化EnterCommandViewController实例（即enterCVS）后，该实例仍然为零，如我文章末尾所示。

代码：

EnterCommandViewController.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;
//    DetectionViewController* detectionViewController;
//      __unsafe_unretained id<EnterCommandDelegate> delegate;
}

-(void)sendMessage:(NSString*)message;

-(id)initWithDelegate:(id)delegateToBe;
- (IBAction)cancelPressed;

- (IBAction)savePressed;


@property (nonatomic,weak) id<EnterCommandDelegate> delegate;  //assign  replaced

@end

#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

试着把它改成

enterCVC = [[EnterCommandViewController alloc] initWithDelegate:self];

---

什么是RscMgr类？另外，哪个视图控制器是初始视图控制器，以及如何从第一个视图控制器转到第二个视图控制器？RscMgr.h是我正在使用的另一个第三方库。DetectionView是初始视图，如何从DetectionViewController转到EnterCommandViewController？你在故事板上做这些吗？您正在使用segue吗？我在DetectionView底部的工具栏中有一个条形按钮项（名为“设置”），它将segue（show）进入CommandView您不应该使用alloc init创建控制器的实例。segue创建实例。您应该实现prepareForSegue，在这里您可以获得对目标视图控制器的引用，并将自己设置为那里的代理。

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

@implementation DetectionViewController
@synthesize showReceivedCommand;
@synthesize enterCVC;

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

-(void) viewDidLoad{
[super viewDidLoad];
if(showReceivedCommand){
showReceivedCommand.text=@"Initial text";
    NSLog(@"UILAbel in ViewDidload is not nil");
}else {
    NSLog(@"UILAbel in viewDidload is nil");
}
enterCVC = [[EnterCommandViewController alloc] init];
if(enterCVC.delegate) NSLog(@"X nil");
[enterCVC setDelegate:self];

}

#pragma mark - EnterCommandDelegate function(s)

-(void)commandEntered:(NSString *)command{

dispatch_async(dispatch_get_main_queue(), ^{
    if(showReceivedCommand){
        NSLog(@"UILabel is not nil");
    }else{NSLog(@"UILabel is nil");}


    showReceivedCommand = [[UILabel alloc] init];
    NSLog(@"command received: %@",command);
    showReceivedCommand.text = command;
   [showReceivedCommand setNeedsDisplay];
            NSLog(@"text in showReceivedCommand is %@",showReceivedCommand.text);
    });
 }
@end

self    DetectionViewController *   0x15c50e850 0x000000015c50e850
UIViewController    UIViewController        
showReceivedCommand UILabel *   0x15c510650 0x000000015c510650
enterCVC    EnterCommandViewController *    0x15c611360 0x000000015c611360
showReceivedCommand UILabel *   0x15c510650 0x000000015c510650
enterCVC    EnterCommandViewController *    0x15c611360 0x000000015c611360
UIViewController    UIViewController        
rscMgr  RscMgr *    nil 0x0000000000000000
inputTextField  UITextField *   nil 0x0000000000000000
connected   BOOL    NO  false
delegate    id  0x0 0x0000000000000000

enterCVC = [[EnterCommandViewController alloc] init]

enterCVC = [[EnterCommandViewController alloc] initWithDelegate:self];