Question

我正在尝试使用Xcode 4编写我的第一个iPad应用程序：它基于带有两个视图的“选项卡式应用程序”模板。在第一个视图中，用户选择一个城市（标签显示选择），在第二个视图中，有一个IBOutletCollection（UITextField）NSArray * playersData。我想将第一个视图中选择的城市设置为第二个视图中的默认城市。我检查了故事板连接，它们似乎没问题。

我一无所获。有什么想法吗？

第一种观点：
#import

@interface pruebaF1FirstViewController : UIViewController
- (IBAction)selectCity:(UIButton *)sender;
@property (weak, nonatomic) IBOutlet UILabel *citySelected;
@end

第一个视图实现： #import“pruebaF1FirstViewController.h” #import“pruebaF1SecondViewController.h”

@interface pruebaF1FirstViewController ()
@property pruebaF1SecondViewController *secondView;
@end

@implementation pruebaF1FirstViewController
@synthesize citySelected;
@synthesize secondView;

- (void)viewDidLoad
...

- (IBAction)selectCity:(UIButton *)sender {
    NSString *currentCity =[sender currentTitle];
    citySelected.text=@"";
    citySelected.text =[citySelected.text stringByAppendingString:currentCity];

    /*writes null*/
    secondView.defaultCity.text=[NSString stringWithFormat:@"%@" ,currentCity];
    NSLog(@"%@",secondView.defaultCity.text);
}
@end

第二个视图标题

#import <UIKit/UIKit.h>
@interface pruebaF1SecondViewController : UIViewController <UITextFieldDelegate> 

@property (strong, nonatomic) IBOutletCollection(UITextField) NSArray *playersData;
@property (retain, nonatomic) IBOutlet UITextField *defaultCity;

- (IBAction)eraseData:(UIButton *)sender;
- (IBAction)savePlayersData:(UIButton *)sender;

- (IBAction)termsPopUp:(UIButton *)sender;

/*- (void)writeDefaultCity:(NSString *)currentCity;*/
@end

第二个视图实现 #import“pruebaF1SecondViewController.h” #import“pruebaF1FirstViewController.h”

@interface pruebaF1SecondViewController ()
@property (nonatomic, strong)pruebaF1FirstViewController    *prueba;
@end

@implementation pruebaF1SecondViewController
@synthesize playersData;
@synthesize defaultCity;
@synthesize prueba;

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)viewDidUnload
{
    [self setPlayersData:nil];
    [self setDefaultCity:nil];
    [super viewDidUnload];
}

/* Return or Done button dismiss keyboard*/
-(BOOL)textFieldShouldReturn:(UITextField *)boxes
{
    for (UITextField *boxes in playersData) {
        [boxes resignFirstResponder];
    }
    return YES;
}

....

/*Trying to get city's name from first view in two ways*/

/*-(void)setDefaultCity
{ 
 NSString *defecto=prueba.citySelected.text;
 self.defaultCity.text = defecto;
}*/
- (IBAction)eraseData:(UIButton *)sender {

    for (UITextField *boxes in playersData) {
        boxes.text = @" ";
        }
}
/*
-(void)writeDefaultCity:(NSString *)currentCity
{       
    defaultCity.text =[NSString stringWithFormat:@"%@" ,currentCity]; 
    NSLog(@"Ciudad elegida: %@",currentCity);
}*/
....
@end

Answer 1

视图通常在设备上显示之前不会加载，并且在不可见以节省内存时可以随时卸载。这意味着当您设置'defaultCity'的'text'属性时，尚未创建该标签。

相反，你应该为pruebaF1SecondViewController添加一个NSString *属性，并在viewDidLoad中设置defaultCity标签的值：

在标题中：

@property (nonatomic, weak) UILabel *defaultCityLabel;
@property (nonatomic, strong) NSString *defaultCity;

在实施中

- (void)viewDidLoad
{
    [super viewDidLoad];
    defaultCityLabel.text = defaultCity;
}

在第一个视图控制器中，指定字符串值而不是标签值。

UITextField：从标签设置文本

1 个答案: