Question

我对Objective C和Xcode很新，可能只是做了一些愚蠢的错误，但我尝试了很多不同的建议而无法让它们起作用。

简而言之，我想在现有的UIViewController上调用一个方法，当在另一个UIViewController中按下一个按钮时。

（有点背景：两个屏幕是主屏幕和菜单屏幕。用户向上滑动以查看菜单，然后当完成按钮时按下我希望菜单屏幕将一个字符串变量（在这种情况下为URL）发送到主屏幕中的方法，然后主屏幕在UIWebView中显示URL。

我尝试将方法/ URL变量放在AppDelegate / MainViewController中并合成它们。我还尝试使MenuViewController成为MainViewCOntroller的子类，并使用[super readFile：url]调用该方法，该方法已编译但我认为它不会调用现有的MainViewController对象，因为webview没有出现。 / p>

我将粘贴下面代码的相关位:(感谢您的帮助！）

MainViewController.h

#import <UIKit/UIKit.h>

@interface MainViewController : UIViewController {
IBOutlet UIWebView *vCodeView;
}

- (void)readFile:(NSString *)newURL;

@end

MainViewController.m

#import "MainViewController.h"
#import "MenuViewController.h"

@interface MainViewController ()

@end

@implementation MainViewController

- (void)readFile:(NSString *)newURL {
    vCodeView.hidden = NO;

    // seperate url by full stops
    NSArray *splitURL = [newURL componentsSeparatedByString:@"."];
    // find extension of file
    NSString *extension = [splitURL objectAtIndex:([splitURL count]-1)];

    // DO SOME OTHER STUFF WITH URL THEN DISPLAY CONTENT IN UIWEBVIEW
}

- (void)swipeUpRecognised {
    MenuViewController *menuView = [[MenuViewController alloc] initWithNibName:@"MenuViewController" bundle:nil];
    menuView.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    [self presentViewController:menuView animated:YES completion:nil];
}

MenuViewController.h

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

@interface MenuViewController : UIViewController {
    IBOutlet UIBarButtonItem *bDone;
    IBOutlet UITextField *fUser;
    IBOutlet UITextField *fPass;
    IBOutlet UITextField *fAddress;
    IBOutlet UITextField *fAutoConnectAddress;
}

- (IBAction)bDonePressed;

@end

MenuViewController.m

#import "MenuViewController.h"
#import "MainViewController.h"

@interface MenuViewController ()

@end

@implementation MenuViewController

- (IBAction)bDonePressed {

    NSString *user = @"admin";
    NSString *pass = @"password";
    NSString *path = @"54.246.90.95/repos/project1/trunk/dir1/test.c";

    // url of file
    NSArray *pathArray = [[NSArray alloc] initWithObjects:@"http://", user, @":", pass, @"@", path, nil];
    NSString *url = [pathArray componentsJoinedByString:@""];

    //call the method here passing in url

    [self dismissViewControllerAnimated:YES completion:nil];
}

Answer 1

在这种特殊情况下，您可以在dismissViewControllerAnimated来电之前输入以下内容，它应该有效：

if(self.presentingViewController && [self.presentingViewController respondsToSelector:@selector(readFile:)]) {
    [(id)self.presentingViewController readFile:url];
}

一般来说，您真正想要的是Delegation。

因此，为了更清洁的实现，请尝试以下方法：

MenuViewController.h

@protocol MenuViewControllerDelegate <NSObject>
    - (void)menuViewControllerFinishedWithURL:(NSURL *)url;
@end

@interface MenuViewController : UIViewController {
    @property id<MenuViewControllerDelegate> delegate;
// ...

MenuViewController.m

- (IBAction)bDonePressed {
    // ...

    if(self.delegate) {
        [self.delegate menuViewControllerFinishedWithURL:url];
    }

    [self.presentingViewController dismissViewControllerAnimated:YES completion:nil];
}

MainViewController.m

@interface MainViewController () <MenuViewControllerDelegate>

@end

// ...

- (void)swipeUpRecognised {
    MenuViewController *menuView = [[MenuViewController alloc] initWithNibName:@"MenuViewController" bundle:nil];
    menuView.delegate = self;
    menuView.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    [self presentViewController:menuView animated:YES completion:nil];
}

Answer 2

为了调用MainViewController方法，它应该很简单：

将MainViewController.h包含在MenuViewController.h中。

将此代码段称为：

NSString * vcid = @""; //put id you have assigned to your MainViewController. This should be in your storyboard. If it is empty, fill it with proper name, then use it here.
UIStoryboard *storybord = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
MainViewController *mainvc =[storybord instantiateviewcontrollerwithidentifier:vcid];
[mainvc method];

请注意，必须在MainViewController.h文件中声明method才能调用它。

那就是说，我想知道你的设计是否真的需要为菜单设置单独的视图控制器。如果您想为选择提供一些按钮组，请考虑包含所有这些按钮的UIView。然后应该在swipeUpRecognised中弹出这个UIView。

Answer 3

此代码适合您... 像这样修改你的代码....

<强> MainViewController.h

#import <UIKit/UIKit.h>

@interface MainViewController : UIViewController {
IBOutlet UIWebView *vCodeView;
}

- (void)readFile:(NSString *)newURL;

@end

<强> MainViewController.m

#import "MainViewController.h"
#import "MenuViewController.h"

@interface MainViewController ()

@end

@implementation MainViewController

- (void)readFile:(NSString *)newURL {
    vCodeView.hidden = NO;

    // seperate url by full stops
    NSArray *splitURL = [newURL componentsSeparatedByString:@"."];
    // find extension of file
    NSString *extension = [splitURL objectAtIndex:([splitURL count]-1)];

    // DO SOME OTHER STUFF WITH URL THEN DISPLAY CONTENT IN UIWEBVIEW
}

- (void)swipeUpRecognised {
    MenuViewController *menuView = [[MenuViewController alloc] initWithNibName:@"MenuViewController" bundle:nil];
menuView.delegate = self;
    menuView.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    [self presentViewController:menuView animated:YES completion:nil];
}

<强> MenuViewController.h

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

@interface MenuViewController : UIViewController {
    IBOutlet UIBarButtonItem *bDone;
    IBOutlet UITextField *fUser;
    IBOutlet UITextField *fPass;
    IBOutlet UITextField *fAddress;
    IBOutlet UITextField *fAutoConnectAddress;
}
@property(nonatomic, retain) MainViewController *delegate;
- (IBAction)bDonePressed;

@end

<强> MenuViewController.m

#import "MenuViewController.h"
#import "MainViewController.h"

@interface MenuViewController ()

@end

@implementation MenuViewController
@synthesize delegate = _delegate;
- (IBAction)bDonePressed {

    NSString *user = @"admin";
    NSString *pass = @"password";
    NSString *path = @"54.246.90.95/repos/project1/trunk/dir1/test.c";

    // url of file
    NSArray *pathArray = [[NSArray alloc] initWithObjects:@"http://", user, @":", pass, @"@", path, nil];
    NSString *url = [pathArray componentsJoinedByString:@""];

    //call the method here passing in url
    [self.delegate readFile:url];

    [self dismissViewControllerAnimated:YES completion:nil];
}

如何在现有对象上调用来自不同类的方法（Obj C）

3 个答案:

MenuViewController.h

MenuViewController.m

MainViewController.m