Question

我不明白，因为错误显示“协议中的方法未实现”

myProtocol.h

#import <Foundation/Foundation.h>

@protocol myProtocol <NSObject>

-(UIImage *)transferImage;

@end

ViewController.h

#import "SecondClass.h"

@interface ViewController : UIViewController<myProtocol, UINavigationControllerDelegate>

{
UIView *view;

}

@property (nonatomic,retain) UIImageView *imageView;

- (IBAction)sendImage:(id)sender;

@end

ViewController.m

#import "ViewController.h"
#import "SecondViewController.h"
#import "myProtocol.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];

_imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"VoodooVibe@2x.png"]];

[view addSubview:_imageView];

NSLog(@"I am in VC.m");
}

-(UIImage *)transferImage{
NSLog(@"I am in transferImage");
return _imageView.image;}
- (IBAction)sendImage:(id)sender {
SecondViewController *secClass = [[SecondViewController alloc]init];

secClass.delegate = self; [secClass callTransfer]; NSLog（@“我在发件人中”）; [self.navigationController pushViewController：secClass animated：YES];}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end

SecondViewController.h

#import <UIKit/UIKit.h>

#import "myProtocol.h"

#import "ViewController.h"

@interface SecondViewController :               UIViewController<myProtocol,UINavigationControllerDelegate> {

UIView *secondView;

IBOutlet UIImageView *myImage;

id <myProtocol> myDelegate;
}

@property (nonatomic,strong) UIImageView *myImage;

@property(nonatomic,weak) id delegate;

-(void)callTransfer;

@end

SecondViewController.m

#import "SecondViewController.h"

#import "ViewController.h"

#import "myProtocol.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

@synthesize delegate,myImage;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
    // Custom initialization
}
return self;
}

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.

[secondView addSubview:myImage];
}
-(void)callTransfer

{
myImage.image=[delegate performSelector:@selector(transferImage)];

myImage.image=[UIImage imageNamed:@"VoodooVibe@2x.png"];

NSLog(@"%@",myImage.image);

NSLog(@"I am in call transfer");

}


- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end

Answer 1

您在delegate内调用了SecondViewController方法但未插入它。如果您收到... not implemented之类的警告，则表示您忘了添加方法。你可以插入像这样的方法

-(UIImage *)transferImage{
    //do something here if delegate has been called
}

或者您只需在delegate块内的方法上方添加一个参数：

@optional

如果您不指定，则所有方法都将设置为@required initial。

Answer 2

它就像你在协议实现中声明了一个方法一样简单但没有实现相同的方法。在您的第二个VC中，您尚未实现“转移图像”方法。所以编译器正在生成警告

协议中的方法未在iOS中实现

2 个答案: