Objective C属性语法

Question

我对我的代码有快速提问：

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

由于某种原因在线：

@property (retain, nonatomic) UIImage *image;

我得到一个错误，说“具有'保留（或强）'属性的属性必须是对象类型”。

我的ViewController.m类是我创建三个Animal对象的地方，并使用我在Animal.h中创建的UIImage属性，并将每个Animal对象UIImage属性设置为我在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

出于某些原因，在Animal.h中，我不断收到“带有'保留（或强）'属性的属性必须是对象类型”的错误。 我不太确定这些属性中的保留或强大含义，但是有人可以向我解释我在代码中做错了什么。 非常感谢你的帮助。

Answer 1

UIImage属于UIKit，因此导入UIKit而不是Foundation