Question

好的，所以我有一个包含以下文件的小程序;
- HomeViewController（.h .m .xib）
- DataViewController（.h .m .xib）
- AppDelegate（.h .m）
- 人（.h .m）[OBJECT]
+支持文件等......

假设我通过HomeViewController中的文本框和其他输入获取用户输入，并将它们设置为Person实例（年龄，等级等）的属性，如何从DataViewController访问它们（相同的实例）显示它们？

以下是来自HomeViewController.h和.m
的代码片段 .H

@interface HomeViewController : UIViewController {

    IBOutlet UIButton *done;

    BOOL standardRes;
}

@property (nonatomic) int newAge;
@property (nonatomic) int newGrade;

-(IBAction)doneButtonPressed;

@end

.m

@implementation HomeViewController
@synthesize newAge, newGrade;

-(IBAction)doneButtonPressed{
    Person *user = [[Person alloc]init]; //Creating an instance of Person called user
    user.age = newAge; //Do I even need this if I use setters and getters in person.m?
    user.grade = newGrade; //Do I even need this if I use setters and getters in person.m?
    NSLog(@"Age: %i, Grade: %i", user.age, user.grade); //Testing with NSLog

    newAge = 175;
    [user setAge:(int)newAge]; //Calling setter method for property 'age' in Person.m

    DataViewController *vc = [[DataViewController alloc]init];
    [self.navigationController pushViewController:vc animated:YES];
}

这里有一点Person.h和.m

@interface Person : NSObject {

}

@property (nonatomic, getter = age, setter = setAge:) int age;
@property (nonatomic) int grade;

@end

@implementation Person
@synthesize age, grade;

-(void)setAge: (int) newAge {
    age = newAge;
}

-(int)age {
    return age;
}

@end

注：
- 使用导航控制器
- iOS 6
- xCode 4.5.1
+如果您需要更多信息，请告诉我们！ :)

附：我对这些东西有点新意，所以这可能是一个愚蠢的问题;）

Answer 1

而不是

DataViewController *vc = [[DataViewController alloc]init];

创建自己的初始值设定项，并传入Person对象。即。

<强> DataViewController.h

- (id)initWithPerson:(Person*)person;

// Need a way to store it, either through a property
@property (nonatomic, strong) Person* person;

<强> DataViewController.m

// Or you can store it as an instance variable, via Class Extension
@interface DataViewController() {
    Person* m_person;
}
@end

// Either way you store it, do it here
-(id)initWithPerson:(Person*)person {
    self = [super init];
    if (self) {
        self.person = person;
        // OR
        m_person = person;
    }
    return self;
}

<强> HomeViewController.m

-(IBAction)doneButtonPressed {
    Person *user = [[Person alloc]init]; //Creating an instance of Person called user
    user.age = newAge; //Do I even need this if I use setters and getters in person.m?
    user.grade = newGrade; //Do I even need this if I use setters and getters in person.m?
    NSLog(@"Age: %i, Grade: %i", user.age, user.grade); //Testing with NSLog

    newAge = 175;
    [user setAge:(int)newAge]; //Calling setter method for property 'age' in Person.m

    DataViewController *vc = [[DataViewController alloc]initWithPerson:user];
    [self.navigationController pushViewController:vc animated:YES];
}

Answer 2

我可以想到几种方法来做到这一点。

1-在HomeViewController中创建一个包含Person对象的Container或List 然后，您可以在DataViewController中调用此列表，并使用get（）方法获取所需的人

2-如果你的应用程序中只需要一个人（如果你在应用程序中需要多个人对象，这将无法工作）你可以让人成为单身人士，然后每次你尝试在你编程时创建一个Person对象将首先检查此对象的实例是否已经存在，如果一个实例不存在，它将返回一个新实例，但如果一个人对象已经存在，它将只返回现有人。

Here是singleton patern的解释和示例代码

在View Controllers之间共享对象实例

2 个答案: