Question

我有一个带有UIViewController的{{1}}，它创建了一个我希望传递给我的RootViewController（ BL_MainViewController ）的字符串。

我的策略是使用委托模式，但我无法弄清楚我在哪里出错了。如果我的RootViewController是使用Storyboard创建的，我如何告诉它 BL_MainViewController.BL_SetTimerViewController = self 我在哪里设置它（猜测：ViewDidLoad）？

BL_SetTimerViewController.h （IB中由模态segue呈现的子VC）

UIPickerView

BL_SetTimerViewController.m

@protocol BL_SetTimerViewControllerDelegate

-(void) updateLabelWithString:(NSString *)string;

@end

@interface BL_SetTimerViewController : UIViewController{
  ... // some ivars
}

@property (assign, nonatomic) id <BL_SetTimerViewControllerDelegate> delegate;

@end

BL_MainViewController.h （根VC）

@implementation BL_SetTimerViewController
...
@synthesize delegate;
...
- (IBAction)setTimerAndDismissViewController:(id)sender {

    // does some stuff, then:

    [self.delegate updateLabelWithString:@"TEST"];
    [self dismissViewControllerAnimated:YES completion:nil];

}

BL_MainViewController.m

#import "BL_SetTimerViewController.h"

@interface BL_MainViewController : UIViewController <BL_SetTimerViewControllerDelegate>{
...
}


@end

Answer 1

在你的BL_MainViewController.m

中

- (void)viewDidLoad {
    [super viewDidLoad];

}
-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    self.pLabel.text=GlobleSting;
}

-(void)updateLabelWithString:(NSString *)string {
    GlobleSting = string; //declare in .h file
}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"YoursegueIdentifir"]) {
        BL_SetTimerViewController *settimerVC =
        segue.destinationViewController;
        settimerVC.delegate = self;
    }
}

Answer 2

代表的超级简单测试应用程序（注意很多东西都被遗漏了，因为它很快被抛到一起），这对我有用。（请注意，委托很弱，不能分配。如果你的目标是iOS 5+ ，使用弱代表）

SimpleProtocol.h

@protocol SimpleProtocol <NSObject>

- (void)updateText:(NSString *)text;

@end

ViewController.m

#import "ViewController.h"

#import "SecondViewController.h"
#import "SimpleProtocol.h"

@interface ViewController ()<SimpleProtocol>

@property (nonatomic, weak) IBOutlet UILabel *label;

@end

@implementation ViewController

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    SecondViewController *vc = (SecondViewController *)segue.destinationViewController;
    vc.delegate = self;
}

- (void)updateText:(NSString *)text
{
    self.label.text = text;
}

@end

SecondViewController.m

#import "SimpleProtocol.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [NSTimer scheduledTimerWithTimeInterval:3 target:self selector:@selector(timerFire:) userInfo:nil repeats:NO];
}

- (void)timerFire:(NSTimer *)timer
{
    NSString *text = [NSString stringWithFormat:@"Test %@", @(arc4random())];
    [self.delegate updateText:text];
    [self.navigationController popViewControllerAnimated:YES];
}

@end

无法在实现中引用委托协议

2 个答案: