传递变量并切换视图iOS / Xcode

Question

所以，我对iOS / Obj-C和Xcode非常陌生，我正在尝试通过构建一个简单的选项卡式视图应用程序来学习，该应用程序需要一些用户变量，将用户移动到下一个视图并显示变量。

目前，我有第一个视图 - 用户选择两个日期。我已成功将这两个日期记录到控制台。我还没有完全理解在视图之间移动的概念。

我想要帮助的是 - 在 - （IBAction）submitDates函数中，将用户移动到下一个视图并将变量传递到该视图 - 并简单地将变量记录到控制台。 /强>

注意：第二个视图文件（JPSecondViewController.m和JPSecondViewController.h尚未被触及）。

提前非常感谢任何帮助/指导！

我的JPFirstViewController.m文件

//  JPFirstViewController.m
//  Vacay
//

#import "JPFirstViewController.h"
#import "JPSecondViewController.h"

@interface JPFirstViewController ()

@end

@implementation JPFirstViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

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

- (IBAction)submitDates {


    //Save the selected date variables
    NSDate *dateFromPicker = [_fromDate date];
    NSDate *endDateFromPicker = [_endDate date];
    NSLog(@"From date: %@ and end date: %@", dateFromPicker, endDateFromPicker);

    //Move user to second view controller

}

@end

我的JPFirstViewController.m文件

//  JPFirstViewController.h
//  Vacay
/

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

@interface JPFirstViewController : UIViewController
@property (strong, nonatomic) IBOutlet UIDatePicker *endDate;
@property (strong, nonatomic) IBOutlet UIDatePicker *fromDate;
- (IBAction)submitDates;

@end

Answer 1

有几种传递变量的方法，这是最简单的方法之一。

- (IBAction)submitDates {
    //Save the selected date variables
    NSDate *dateFromPicker = [_fromDate date];
    NSDate *endDateFromPicker = [_endDate date];
    NSLog(@"From date: %@ and end date: %@", dateFromPicker, endDateFromPicker);

    //Create an instance of the second view controller
    // If you are using NIBs
    JPSecondViewController *secondViewController = [[JPSecondViewController alloc] init];

    //// If you are using storyboards, then you will need to know what the storyboard identifier is for JPSecondViewController. 
    //NSString *identifier = @"<Second Storyboard Identifier>";
    //JPSecondViewController *secondViewController = [self.storyboard instantiateViewControllerWithIdentifier:identifier];

    //Fill in all the data need for the second view controller
    secondViewController.fromDate = dateFromPicker;
    secondViewController.endDate = endDateFromPicker;

    //Show the second view controller
    // Option 1: Add the second view controller to a navigation controller
    [self.navigationController pushViewController:secondViewController animated:YES];

    //// Option 2: Show the second view controller as a modal view controller
    //[self presentViewController:secondViewController animated:YES completion:nil];
}

这将创建第二个视图控制器填充值，并以两种方式之一呈现第二个视图控制器。如果第一个视图控制器嵌入在导航控制器中，那么您只需将第二个视图控制器添加到导航堆栈即可。如果第一个视图控制器不在导航控制器中，则将其显示为模态。

Answer 2

您可以使用各种方法在类之间传递变量

1. 单身人士（我更喜欢）
2. NSUserDefaults的