多个 UILabel 实例

Posted 2023-02-27

【中文标题】多个 UILabel 实例

【英文标题】：Multiple UILabel instances

【发布时间】：2013-09-09 00:26:26

【问题描述】：

我正在创建 UILabel 的多个实例以显示在具有许多标签的地图上，并允许用户返回所选标签的 ID 或标签号。下面的代码只返回最后创建的实例，可能是由于相同的变量“newCity”。

这两个实例将从 pList 动态填充数据，我将循环通过该 pList 来获取标签的城市、idNumber 和 x 和 y 位置。每次城市的数量都会不同，甚至可能会动态变化。为了清楚起见，显示了两个。

问题是如何为被点击的正确标签获取正确的 idNumber？ 我搜索了很多地方，但没有找到可以在不引起其他问题的情况下工作的解决方案。如何创建新实例并仍然获得正确的实例？

还要注意下面的 tapGestureRecognizer 有 tapGesture 和 tapGesture2 名称。它不适用于同一个。如何使用带有一个名称的 tapGesture 并识别哪个标签？

除非没有其他方法，否则我宁愿使用标签而不是按钮。我什至可以添加一个 touchesBegan 或 touchesMoved 来调整我不想与标签中的 tapGesture 冲突的子视图。

感谢您的帮助。

WBCitiesView.h

@interface WBCitiesView : UIViewController 

    UIView      *subView;
    int         resultNumber;


@property(nonatomic, strong) UIView *subView;
@property int resultNumber;

- (void) touchUp:(id)sender;

@end

WBCitiesView.m

#import "WBCitiesView.h"
#import "WBCities.h"


@interface WBCitiesView ()

@end

@implementation WBCitiesView

@synthesize subView, resultNumber;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) 

    
    return self;



WBCities *newCity;


- (void)viewDidLoad

    [super viewDidLoad];

    CGRect mapFrame = CGRectMake(20, 30, 250, 300);
    subView = [[UIView alloc]initWithFrame:mapFrame];
    subView.backgroundColor = [UIColor grayColor];
    subView.alpha = .5;
    subView.autoresizesSubviews=YES;
    UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc]  initWithTarget:subView action:@selector(swipe:)];///was self
    [subView addGestureRecognizer:swipe];
    [self.view addSubview:subView];




    newCity =[[WBCities alloc] initWithFrame:CGRectMake(50, 20, 100, 30)];
    newCity.city = @"CityA";
    newCity.idNumber = 1111;
    newCity.size = 0;
    [newCity setBackgroundColor:[UIColor blueColor]];
    [newCity setText:newCity.city];
    [newCity setTag:newCity.idNumber];
    newCity.userInteractionEnabled = YES;
    UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(touchUp:)];
    [newCity addGestureRecognizer:tapGesture];
    [subView addSubview:newCity];


    newCity =[[WBCities alloc] initWithFrame:CGRectMake(100, 70, 100, 30)];
    newCity.city = @"CityB";
    newCity.idNumber = 2222;
    newCity.size = 1;
    [newCity setBackgroundColor:[UIColor yellowColor]];
    [newCity setText:newCity.city];
    [newCity setTag:newCity.idNumber];
    newCity.userInteractionEnabled = YES;
    UITapGestureRecognizer *tapGesture2 = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(touchUp:)];
    [newCity addGestureRecognizer:tapGesture2];
    [subView addSubview:newCity];



-(void) touchUp:(id)sender


    resultNumber = [newCity returnIdNumber];

WBCities.h

@interface WBCities : UILabel
    NSString    *city;
    int         idNumber;
    BOOL        size;


@property (nonatomic, strong) NSString *city;
@property (nonatomic) int idNumber;
@property (nonatomic) BOOL size;

-(int)returnIdNumber;

@end

WBCities.m

#import "WBCities.h"
#import "WBCitiesView.h"

@implementation WBCities

@synthesize city, idNumber, size;

-(id)init
    self = [super init];
    if (self)

    
    return self;


-(int)returnIdNumber

    return idNumber;


@end

【参考方案1】：

用下面的代码替换你的 -(void) touchUp:(id)sender 方法

-(void) touchUp:(id)sender

    UITapGestureRecognizer *tapGesture = (UITapGestureRecognizer*)sender;
    WBCities *cityLabel = (WBCities*)tapGesture.view;
    resultNumber = [cityLabel returnIdNumber];

【参考方案2】：

要获得正确的 idNumber，您应该执行以下操作：

-(void) touchUp:(id)sender

    WBCities* city =(WBCities*) sender;

    resultNumber = [city tag];

idNumber 的使用实际上是多余的，你应该使用 tag 字段来代替。

为了避免必须为每个 WBCity 创建不同的手势识别器，我建议更改 WBCities 以扩展 UIControl 而不是 UILabel，然后像这样初始化它：

    newCity =[[WBCities alloc] initWithFrame:CGRectMake(50, 20, 100, 30)];
    newCity.city = @"CityA";
    newCity.tag = 1111;
    newCity.size = 0;
    [newCity setBackgroundColor:[UIColor blueColor]];
    [newCity setCity:newCity.city];
    [newCity addTarget:self action:@selector(touchUp:) forControlEvents:UIControlEventTouchUpInside];
    [subView addSubview:newCity];

【讨论】：

-(void) touchUp:(id)sender WBCities cityLabel = (WBCities)sender.view resultNumber = [newCity returnIdNumber];

这行得通，但是从 UIControl 子类化时无法使用 setText 方法。我试图解决它但无法这样做，显然这在 UILabel 中可用。我能够在我调用的方法中使用这个答案， UITapGestureRecognizer tapGesture = (UITapGestureRecognizer)sender; WBCities cityLabel = (WBCities)tapGesture.view; resultNumber = [cityLabel returnIdNumber];谢谢。

使用 setCity 代替 setText。