Objective c 目标C属性语法

我有一个关于我的代码的快速问题：

这是我的Animal.h头文件：

#import <Foundation/Foundation.h>

@interface Animal : NSObject 

@property (nonatomic) int age;
@property (nonatomic, strong) NSString *name;
@property (nonatomic,strong) NSString *breed;
@property (retain, nonatomic) UIImage *image;


-(void) bark;

-(void)barkNumTimes: (int)numOfTimesToBark;

-(void)barknumTimes:(int)numberOfTimes loudly:(bool) isLoud;

-(int) ageInDogYears: (int)humanYears;

@end

我得到一个错误，指出“具有'retain（或strong）'属性的属性必须是对象类型”

在我的ViewController.m类中，我创建了三个动物对象，并使用了在Animal.h中创建的UIImage属性，并将每个动物对象UIImage属性设置为支持文件中的某个图像：

#import "ViewController.h"
#import "Animal.h"
#import "Puppy.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.whichDog = 0;

    Animal *whiteDog = [[Animal alloc]init];

    [whiteDog setName:@"white"];
    [whiteDog setBreed:@"White Dog"];
    whiteDog.image = [UIImage imageNamed:@"whitedog.jpeg"];

    Animal *brownDog = [[Animal alloc] init];
    [brownDog setName:@"brown"];
    [brownDog setBreed:@"Brown Dog"];
    brownDog.image = [UIImage imageNamed:@"browndog.jpeg"];

    Animal *husky = [[Animal alloc] init];
    [husky setName:@"husky"];
    [husky setBreed:@"Husky Dog"];
    husky.image = [UIImage imageNamed:@"husky.jpeg"];

    self.myAnimals = [[NSMutableArray alloc] init];

    [self.myAnimals addObject:whiteDog];
    [self.myAnimals addObject:brownDog];
    [self.myAnimals addObject:husky];

    Puppy *pup = [[Puppy alloc]init];
    [pup setName:@"coby"];
    [pup setBreed:@"Portuguese Water Dog"];
    pup.image = [UIImage imageNamed:@"puppy.jpeg"];
}

- (IBAction)newDogBarButton:(UIBarButtonItem *)sender{

    int numOfDogs = (int)[self.myAnimals count];
    int randomIndex = arc4random() % numOfDogs;

    Animal *randomAnimal = [self.myAnimals objectAtIndex:randomIndex];
    [UIView transitionWithView:self.view duration:1.5 options:UIViewAnimationOptionTransitionCurlDown animations:^{
        self.imageView.image = randomAnimal.image;
        self.carNAme.text = randomAnimal.name;
        self.extra.text = [randomAnimal breed];
    } completion:^(BOOL finished) {

    }];
    sender.title = @"And Another";
    self.whichDog = randomIndex;
}

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

---

由于某种原因，在Animal.h中，我不断得到这样一个错误，即“具有'retain（或strong）'属性的属性必须是对象类型”。我不太清楚这个retain或strong在属性中意味着什么，但是有人能解释一下我在代码中做错了什么吗。非常感谢您的帮助。

UIImage属于UIKit，因此导入UIKit而不是Foundation

是否使用ARC？你为什么把

strong

和

retain

与你的房产混在一起？嗨，我实际上不知道strong和retain是什么意思，这就是为什么我不知道该用哪一个。在引入ARC之前，我们通常使用

retain

。我们现在在ARC中使用

strong

。因此，用

strong

@ClayHorder替换

retain

，您使用的是指南还是教程？因为它可能是过时的。所以在上面添加另一个导入语句：UIKit导入“uiKIT”？不，用<代码> >导入导入< /COD>（或<代码> @导入UIKIT；< /COD>）替换“<代码>导入> <代码>。用UIKit替换基础，UIKit包含基础框架。您可能会使用语法

@import-UIKit好的。我在工作中得到了密码。谢谢你的帮助！哦，所以我觉得我甚至不需要：#导入。
#import "ViewController.h"
#import "Animal.h"
#import "Puppy.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.whichDog = 0;

    Animal *whiteDog = [[Animal alloc]init];

    [whiteDog setName:@"white"];
    [whiteDog setBreed:@"White Dog"];
    whiteDog.image = [UIImage imageNamed:@"whitedog.jpeg"];

    Animal *brownDog = [[Animal alloc] init];
    [brownDog setName:@"brown"];
    [brownDog setBreed:@"Brown Dog"];
    brownDog.image = [UIImage imageNamed:@"browndog.jpeg"];

    Animal *husky = [[Animal alloc] init];
    [husky setName:@"husky"];
    [husky setBreed:@"Husky Dog"];
    husky.image = [UIImage imageNamed:@"husky.jpeg"];

    self.myAnimals = [[NSMutableArray alloc] init];

    [self.myAnimals addObject:whiteDog];
    [self.myAnimals addObject:brownDog];
    [self.myAnimals addObject:husky];

    Puppy *pup = [[Puppy alloc]init];
    [pup setName:@"coby"];
    [pup setBreed:@"Portuguese Water Dog"];
    pup.image = [UIImage imageNamed:@"puppy.jpeg"];
}

- (IBAction)newDogBarButton:(UIBarButtonItem *)sender{

    int numOfDogs = (int)[self.myAnimals count];
    int randomIndex = arc4random() % numOfDogs;

    Animal *randomAnimal = [self.myAnimals objectAtIndex:randomIndex];
    [UIView transitionWithView:self.view duration:1.5 options:UIViewAnimationOptionTransitionCurlDown animations:^{
        self.imageView.image = randomAnimal.image;
        self.carNAme.text = randomAnimal.name;
        self.extra.text = [randomAnimal breed];
    } completion:^(BOOL finished) {

    }];
    sender.title = @"And Another";
    self.whichDog = randomIndex;
}

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