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在我的应用程序中，我正在将图像加载到表格的单元格中。但是，当我滚动表格时，图像消失在表格的视线中（上升），即使我向后滚动也不会出现。

customCell.h

#import <UIKit/UIKit.h>
@interface CustomCell : UITableViewCell<UINavigationControllerDelegate, UIImagePickerControllerDelegate> {
UIViewController *viewController;
UIImageView *imageView;
UIButton *button;
@property (nonatomic, retain) IBOutlet UIImageView *imageView; 
@property (nonatomic, assign)UIViewController *viewController;
@property (nonatomic, retain) IBOutlet UIButton *button;
-(IBAction)selectExistingPicture1;

@end
}

自定义Cell.m

    #import "CustomCell.h"
    @implementation CustomCell
@synthesize imageView;
@synthesize viewController;
@synthesize button;
- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker { 
    [picker dismissModalViewControllerAnimated:YES]; 
} 

- (IBAction)selectExistingPicture1 { 
        if ([UIImagePickerController isSourceTypeAvailable: UIImagePickerControllerSourceTypePhotoLibrary]) {
        UIImagePickerController *picker = [[UIImagePickerController alloc] init];
        picker.delegate = self; 
        picker.allowsImageEditing = YES;
        picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        [self.viewController presentModalViewController:picker animated:YES];
        [picker release];
    } 
    else { 
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error accessing photo library" message:@"Device does not support a photo library" delegate:nil cancelButtonTitle:@"Drat!" otherButtonTitles:nil]; 
        [alert show]; 
        [alert release]; 
    } 
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo {


    UIImage *thumbnail = [image _imageScaledToSize:CGSizeMake(80, 80) interpolationQuality:1];
    /*CGSize newSize = CGSizeMake(80, 80);
    UIGraphicsBeginImageContext( newSize );
    [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();*/
    imageView.image = thumbnail;

    [picker dismissModalViewControllerAnimated:YES]; 


}  

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
    if (self = [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {
        // Initialization code
    }
    return self;
}


- (void)setSelected:(BOOL)selected animated:(BOOL)animated {

    [super setSelected:selected animated:animated];

    // Configure the view for the selected state
}

- (void)dealloc {
    [imageView release];
    [viewController release];
    [button release];

    [super dealloc];
}


@end

cameraViewController.h

#import <UIKit/UIKit.h>

@interface Camera1ViewController : UIViewController <UITableViewDelegate,UITableViewDataSource> {      

}

@end

cameraViewController.m

#import "Camera1ViewController.h"
#import "CustomCell.h"

@implementation Camera1ViewController

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

- (void)viewDidUnload {

    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}


- (void)dealloc {
    [i
    [super dealloc];
}


 #pragma mark Table Data Source Methods 

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { 
    return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { 
    return 25; 
} 

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
     static NSString *CustomCellIdentifier = @"CustomCellIdentifier";

          CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:CustomCellIdentifier];
     if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CustomCellIdentifier] autorelease];
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:self
                                                    options:nil];
         for (id currentObject in nib){
             if ([currentObject isKindOfClass:[CustomCell class]]){
                 cell = (CustomCell *)currentObject;
                 cell.viewController = self;
                 break;
             }
         }

     }
     //dont know what to do here. 
     return cell;

} 

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { 
    return 100; 
} 


- (NSString *)tableView:(UITableView *)tableView 
titleForHeaderInSection:(NSInteger)section { 
    NSString *key = @"Album"; 
    return key; 
} 
@end
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2 回答 2

4

您的问题很可能是由于您重复使用单元格并且当它们返回屏幕时没有正确重新初始化它们。好的，所以当一个单元格在表格视图中超出视图时，它会被卸载以节省内存，当您选择重用一个只有 1 个标识符的单元格时，这意味着每次使用该标识符的单元格出现在屏幕上时，表格视图都会返回该类型的单元格（但它不是您第一次配置的原始单元格）当它返回一轮时，您必须假设它是“脏的”并且您必须重新初始化图像及其内容，如果你不你会得到像您看到的那样不受欢迎的结果。

另一种选择（虽然对于具有大量单元格的表格视图来说不是一个好的选择）是给每个单元格一个唯一的标识符，现在您可以保证您的单元格不会“脏”，因为在标识符和单元格之间存在一对一的映射，向下一方面是您将消耗大量内存，这违背了重用单元的目的（就好像您根本没有重用单元）......希望这会有所帮助

于 2009-12-02T14:40:09.540 回答
0

从上一篇文章中查看您的代码：

NSUInteger s= indexPath.section;
 //[cell setText:[NSString stringWithFormat:@"I am cell %d", indexPath.row]];

 NSUInteger r = indexPath.row;
  cell.imageView.image = nil;
 for (s;s==0;s++)
 for(r;r==0;r++)
 {           
      UIImage *img=imageView.image;
     cell.imageView.image = img;
     }
 return cell;

}

我不确定循环的用途，但是每当需要重绘单元格时，您都将单元格的 UIImageView 设置为imageView.image（我假设 imageView 是您的 UIViewController 的属性），所以本质上您正在用那个单一的 imageView 覆盖已经存在的内容

于 2009-12-03T01:07:15.210 回答