Question

我想在详细视图中的label.text上打印出indexPath.row数字，方法是在UITableView和detailview之间传递数据，但我无法正确执行。

ViewController.h

#import <UIKit/UIKit.h>
#import "SecondViewController.h"


@interface ViewController : UIViewController<UITableViewDataSource,UITableViewDelegate>{
    NSArray *tableItems;
    NSArray *images;

}

@property (nonatomic,retain) NSArray *tableItems;
@property (nonatomic,retain) NSArray *images;

@end

ViewController.m

#import "ViewController.h"
#import <QuartzCore/QuartzCore.h>
#import "SecondViewController.h"

@interface ViewController ()

@end

@implementation ViewController
@synthesize tableItems,images;
- (void)viewDidLoad
{
    [super viewDidLoad];
    tableItems = [[NSArray alloc] initWithObjects:@"Item1",@"Item2",@"Item3",nil];
    images = [[NSArray alloc] initWithObjects:[UIImage imageNamed:@"clock.png"],[UIImage imageNamed:@"eye.png"],[UIImage imageNamed:@"target.png"],nil];
}

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    return tableItems.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

    //Step 1:Check whether if we can reuse a cell
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];

    //If there are no new cells to reuse,create a new one
    if(cell ==  nil)
    { 
        cell = [[UITableViewCell alloc] initWithStyle:(UITableViewCellStyleDefault) reuseIdentifier:@"cell"];
        UIView *v = [[UIView alloc] init];
        v.backgroundColor = [UIColor redColor];
        cell.selectedBackgroundView = v;
        //changing the radius of the corners
        //cell.layer.cornerRadius = 10;

    }

    //Set the image in the row
    cell.imageView.image = [images objectAtIndex:indexPath.row];

    //Step 3: Set the cell text content
    cell.textLabel.text = [tableItems objectAtIndex:indexPath.row];

    //Step 4: Return the row
    return cell;

}

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath{
    cell.backgroundColor = [ UIColor greenColor];
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

    SecondViewController *secondViewController = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];

    [secondViewController printRowNumber:indexPath.row+1];

    NSString *selectedRow = [tableItems objectAtIndex:indexPath.row+1];

    secondViewController.selectedRow = selectedRow;

    //[self.navigationController pushViewController:secondViewController animated:YES];
    [self presentViewController:secondViewController animated:YES completion:NULL];
}
@end

SecondViewController.h

#import <UIKit/UIKit.h>
#import "ViewController.h"


@interface SecondViewController : UIViewController{
    IBOutlet UILabel *lbl;
    NSString *selectedRow;

}
@property (nonatomic,retain) UILabel *lbl;
@property (nonatomic,retain) NSString *selectedRow;

- (IBAction)goBack:(id)sender;

-(void) printRowNumber:(int)num;
@end

SecondViewController.m

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

@synthesize lbl,selectedRow;

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

- (void)viewDidLoad
{
    [super viewDidLoad];
    //[self changeLabel:@"Hello"];
    //lbl.text = @"Hello";
    // Do any additional setup after loading the view from its nib.
}

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

- (IBAction)goBack:(id)sender{

    //ViewController *firstViewController = [[ViewController alloc] initWithNibName:nil bundle:nil];
    //firstViewController.delegate = self;
    [self dismissViewControllerAnimated:YES completion:NULL];
}

-(void) printRowNumber:(int)num{
    lbl.text = selectedRow;
    NSLog(@"%@",lbl.text);
    NSLog(@"%d",num);
}
-(void) changeLabel:(NSString*)str{
    lbl.text = str;
    //lbl.text = @"Hello";
}
@end

不确定如何解决这个问题..需要一些帮助......

Answer 1

我建议您只将当前视图控制器中的值传递给下一个视图控制器，不要从当前控制器调用下一个控制器的功能。它将导致对象的释放。

只需传递该值并立即推送该视图控制器并享受该值。希望对你有效。

Answer 2

[secondViewController printRowNumber:indexPath.row+1];
NSString *selectedRow = [tableItems objectAtIndex:indexPath.row+1];
secondViewController.selectedRow = selectedRow;

如果您在didSelect方法中查看这三行代码，则在不设置selectedRow字符串的情况下调用printRowNumber方法，因此无法使用，请尝试将顺序切换为：

NSString *selectedRow = [tableItems objectAtIndex:indexPath.row+1];
secondViewController.selectedRow = selectedRow;
[secondViewController printRowNumber：indexPath.row + 1];

Answer 3

在SecondViewController中的viewDidLoad中调用-(void) printRowNumber:(int)num方法，并从firstViewController中的[secondViewController printRowNumber:indexPath.row+1];中删除rowDidSelect。

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self printRowNumber:[selectedRow intValue]];
}

试试这可能对你有帮助....

Answer 4

在下面，您需要更改一小段代码。

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

  SecondViewController *secondViewController = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];

  NSString *selectedRow = [tableItems objectAtIndex:indexPath.row+1];

  secondViewController.selectedRow = selectedRow;

  //[self.navigationController pushViewController:secondViewController animated:YES];
  [self presentViewController:secondViewController animated:YES completion:NULL];

  //this is the change you should do.
  [secondViewController printRowNumber:indexPath.row+1];

}

Answer 5

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

    SecondViewController *secondViewController = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];

    NSString *selectedRow = [tableItems objectAtIndex:indexPath.row+1];

    secondViewController.selectedRow = selectedRow;

    [self presentViewController:secondViewController animated:YES completion:^{
        [secondViewController printRowNumber:indexPath.row+1];
    }];
}

在呈现控制器后，将创建SecondViewController中的视图。因此，如果在呈现控制器之前调用-printRowNumber：仍未创建标签。

将数据传递到UITableView中的详细视图

5 个答案: