Question

所以我知道我的问题是我的传输阵列没有正确初始化。我应该把transfer = [[NSMutableArray alloc] init]放在哪里;？

@interface PictureViewController (){

    Poi *labelPoi;

}

@end

@implementation PictureViewController
@synthesize imageX;
@synthesize imageY;
@synthesize name;
@synthesize transfer;


- (id)init
{
    self = [super init];
    if(self) {
        transfer = [[NSMutableArray alloc] init];
    }
    return self;
}
-(id)initWithLabel:(double)imageX andY:(double)imageY withName:(NSString *)name{
    self = [super init];
    if(self){

       // transfer = [[NSMutableArray alloc] init];

        self.imageX = imageX;
        self.imageY = imageY;
        self.name = name;
    }

    return self;
}


/*-(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

    if(self){

        transfer = [[NSMutableArray alloc] init];

        self.imageX = imageX;
        self.imageY = imageY;
        self.name = name;
        NSLog(@"imageX: %f", self.imageX);
        NSLog(@"imageY: %f", imageY);
        NSLog(@"name: %@", name);

    }
    return self;
}*/

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

    NSLog(@"transfer count: %lu",(unsigned long)transfer.count);
    for(int i = 0; i < transfer.count; i++){
        UILabel *label =  [[UILabel alloc] initWithFrame: CGRectMake([[transfer objectAtIndex:i] imageLocationX], [[transfer objectAtIndex:i] imageLocationY], 200, 50)];
        label.text = [[transfer objectAtIndex:i] name];
        label.font = [UIFont systemFontOfSize:14];
        label.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.0];
        [self.view addSubview:label];
        NSLog(@"asdfasdsd");
    }
}


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



- (id)display:(double)imageXX andY:(double)imageYY withName:(NSString *)namee{
    NSLog(@"%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%");
    NSLog(@"imageX: %f",imageXX);
    NSLog(@"imageY: %f", imageYY);
    NSLog(@"name: %@", namee);

    labelPoi = [[Poi alloc] init];
    //transfer = [[NSMutableArray alloc] init];
    labelPoi.imageLocationX = imageXX;
    labelPoi.imageLocationY = imageYY;
    labelPoi.name = namee;
    [transfer addObject:labelPoi];
    NSLog(@"label.x: %f should be: %f", labelPoi.imageLocationX, imageXX);
    NSLog(@"label.y: %f should be: %f", labelPoi.imageLocationY, imageYY);
    NSLog(@"label.name: %@ should be: %@",labelPoi.name,namee);
    NSLog(@"transssssfer: %lu", (unsigned long)transfer.count);

    NSLog(@"asfddfsaasfdfdsfsd %f", [[transfer objectAtIndex:0] imageLocationX]);

    return self;
}

@end

Poi对象由imageLocationX，imageLocationY和name组成，我试图将Poi对象放入名为transfer的数组中，但是每当我尝试访问传输元素时，我都会收到0或null。（id）显示函数从该函数中的不同视图NSMutable alloc多次调用，该数组被重置。

这是输出：

2013-07-19 11:22:06.736 AR_UAV_App[12466:11303] %%%%%%%%%%%%%%%%%%%%%%%%
2013-07-19 11:22:06.736 AR_UAV_App[12466:11303] imageX: 224.485718
2013-07-19 11:22:06.736 AR_UAV_App[12466:11303] imageY: 116.353401
2013-07-19 11:22:06.736 AR_UAV_App[12466:11303] name: Beutel Student Health Center
2013-07-19 11:22:06.736 AR_UAV_App[12466:11303] label.x: 224.485718 should be: 224.485718
2013-07-19 11:22:06.736 AR_UAV_App[12466:11303] label.y: 116.353401 should be: 116.353401
2013-07-19 11:22:06.736 AR_UAV_App[12466:11303] label.name: Beutel Student Health Center should be: Beutel Student Health Center
2013-07-19 11:22:06.737 AR_UAV_App[12466:11303] transssssfer: 0
2013-07-19 11:22:06.737 AR_UAV_App[12466:11303] asfddfsaasfdfdsfsd 0.000000
2013-07-19 11:22:06.737 AR_UAV_App[12466:11303] #############################################################

编辑：.h文件

@interface PictureViewController : UIViewController{
    NSMutableArray *transfer;
}

@property (nonatomic) double imageX;
@property (nonatomic) double imageY;
@property (nonatomic) NSString *name;

@property (nonatomic,retain) NSArray *transfer;
- (IBAction)backView:(id)sender;
- (IBAction)load:(id)sender X:(double)imageX andY:(double)imageY withName:(NSString *)name;

-(id)initWithLabel:(double)imageX andY:(double)imageY withName:(NSString *)name;
-(id)display:(double)imageX andY:(double)imageY withName:(NSString *)name;
@end

Answer 1

这个init方法应该成为“指定的”初始化器：

-(id)initWithLabel:andY:withName:(NSString *)name

（顺便说一句，它根据naming conventions没有正确命名）

designated initializer应正确初始化实例（也就是说，在您的情况下，它可能会初始化数组 transfer ，除非您使用lazy accessor）。

“指定初始化程序”通常是“最专业”的初始化程序 - 也就是说，具有大多数参数的初始化程序。大多数情况下，只有一个和易于识别的指定初始值设定项。

“指定的初始化程序”具有规范形式：

-(id)initWithLabel:(double)imageX andY:(double)imageY withName:(NSString *)name{
    self = [super init];
    if(self){
        // initialization
        ...
    }
}

其他初始化方法（如init方法）应调用指定的初始化程序，如：

- (id)init {
    return [self initWithLabel:0 andY:0 withName:@""];
}

Answer 2

我想有一个问题可能是当你创建这个控制器时，你打电话给：

 -(id)initWithLabel:(double)imageX andY:(double)imageY withName:(NSString *)name

如果你这样做，你正在调用[super init]什么永远不会通过你的类的init方法（你分配数组的地方）。如果你有不同的方法来初始化控制器，我建议你有一个：

commonInit{
   _transfer = [[NSMutableArray] alloc] init];
}

然后为控制器中的每个init方法调用此方法，以确保分配了数组。其他的事情就是在您的控制器的viewDidLoad中分配您的数组。

只是为了知道，你可以“分配”一个数组，而不必通过调用[NSMutableArray arrayWithCapacity:0];

来释放对象。

Answer 3

您是否使用-(id)initWithLabel:(double)imageX andY:(double)imageY withName:(NSString *)name初始化PictureViewController？如果是这样，我可以告诉你问题是什么......

-(id)initWithLabel:(double)imageX andY:(double)imageY withName:(NSString *)name
{
    self = [super init];   // <--- You are likely confused about this line

    .....
}

[super init]未向您的自定义-(id)init方法传递消息。它反而指的是PictureViewController的超类，它可能是UIViewController。

您的问题应该通过在transfer = [[NSMutableArray alloc] init];自定义初始化方法中取消注释initWithLabel:来解决。

Answer 4

创建一个属性（合成它@synthesize transfer = _transfer;），使用惰性实例化，如：

-(NSMutableArray*)transfer
{
   if (!_transfer)
   {
       _transfer=[NSMutableArray array];
   }

   return _transfer;
}

并将其从初始

中删除

试图初始化数组目标-c

4 个答案: