如何清除UIButton背景图像状态？

Question

-(void) btnAction:(id) sender {

    NSString *str =((UIButton*)sender).titleLabel.text;

    NSLog(@"%@",str);
    NSLog(@"%@",[dictionary objectForKey:@"option3"]);

    correctAns=[dictionary objectForKey:@"answer"];

        if(str==[dictionary objectForKey:@"option1"])
{

    selectedAns=@"1";

    if ([selectedAns compare:correctAns]==NSOrderedSame) 
    {
     NSLog(@"this is correct");
    [cell.ansBtn1 setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState:UIControlStateSelected];

     countCorrect++;
     cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect];

    }

    else 
    {

        [cell.ansBtn1 setBackgroundImage:[UIImage imageNamed:@"option_red.png"] forState:UIControlStateSelected];
        cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect];

    }

}
}

初始化tableView

        - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"BeginingCell";

    cell=(BeginingCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];


    if (cell == nil) {

        NSArray *topLevelObjects=[[NSBundle mainBundle] loadNibNamed:@"BeginingCell" owner:self options:nil ];

        for(id CurrentObject in topLevelObjects)
        {
            if ([CurrentObject isKindOfClass:[BeginingCell class]]) {

                cell=(BeginingCell *) CurrentObject;
                cell.selectionStyle = UITableViewCellSelectionStyleNone;


                break;
            }
        }

    }


    if(indexPath.row==0)
    {


       imageURL=[dictionary objectForKey:@"questionImage"];
     //  imageName=[dictionary objectForKey:@"questionImage"];
     // imageURL=@"http://localhost:85/2/";
     // imageURL=[imageURL stringByAppendingString:imageName];

        NSURL *url = [NSURL URLWithString:imageURL];
        NSData *data = [NSData dataWithContentsOfURL:(NSURL *)url];
        UIImage *img = [[UIImage alloc]  initWithData:data];



        cell.lblScoreCurrent.text=[NSString stringWithFormat:@"%d", reloader];

        cell.lblScore.text=@"/30";
        cell.myImageView.image = img;
        cell.SectionTitle.text=[dictionary objectForKey:@"question"];




        [cell.ansBtn1 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];
        [cell.ansBtn1 setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState: UIControlStateSelected];
        [cell.ansBtn1 setBackgroundImage:[UIImage imageNamed:@"option_red.png"] forState: UIControlStateSelected];
}

使用您的代码进行更改：

这次它甚至没有将背景图像从option.jpg更改为绿色/红色。所有点击它总是选项。

* *和我的代码......我没有得到任何错误...... * *我测试了断点它正确地通过所有声明......甚至图像的变化..但我看不到任何背景图像的变化。告诉我接下来的事情......

  -(void) btnAction:(id) sender {

    NSString *str =((UIButton*)sender).titleLabel.text;

NSLog(@"%@",str);
NSLog(@"%@",[dictionary objectForKey:@"option3"]);

correctAns=[dictionary objectForKey:@"answer"];

if([str isEqualToString:([dictionary objectForKey:@"option1"])])

{

    selectedAns=@"1";

    if ([selectedAns isEqualToString:correctAns]) 
    {
     NSLog(@"this is correct");
     [((UIButton*)sender) setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState:UIControlStateSelected];

     countCorrect++;
     cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect];

    }

    else 
    {

        [((UIButton*)sender) setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState:UIControlStateSelected];
        cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect];

    }

}

所有的逻辑都没问。即使我正在计算得分......我测试了......只是这个图像问题不起作用....请给我一个方法.....我是全新的iphone ....学习它..如果有任何错误或不好的做法，请给我适当的指导...

使用您的代码后：

按钮aciton的代码：

    -(void) btnAction:(id) sender {

((UIButton *)sender).selected=FALSE;
NSString *str =((UIButton*)sender).titleLabel.text;
correctAns=[dictionary objectForKey:@"answer"];

if([str isEqualToString:([dictionary objectForKey:@"option1"])])

{

    selectedAns=@"1";
    NSLog(@"Selected Ans = %@",selectedAns);
    NSLog(@"Correct = %@",correctAns);


    if ([selectedAns isEqualToString:correctAns]) 
    {
     NSLog(@"this is correct");

     [((UIButton*)sender) setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState:UIControlStateSelected];

    //  sleep(3);

     countCorrect++;
     cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect];

    }

    else 
    {

        [((UIButton*)sender) setBackgroundImage:[UIImage imageNamed:@"option_red.png"] forState:UIControlStateSelected];



        cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect];

    }

    ((UIButton*)sender).selected = true;

}

tableView Indexpath中的

代码：

  - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

static NSString *CellIdentifier = @"BeginingCell";

cell=(BeginingCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];


if (cell == nil) {

    NSArray *topLevelObjects=[[NSBundle mainBundle] loadNibNamed:@"BeginingCell" owner:self options:nil ];

    for(id CurrentObject in topLevelObjects)
    {
        if ([CurrentObject isKindOfClass:[BeginingCell class]]) {

            cell=(BeginingCell *) CurrentObject;
            cell.selectionStyle = UITableViewCellSelectionStyleNone;


            break;
        }
    }

}


if(indexPath.row==0)
{


   imageURL=[dictionary objectForKey:@"questionImage"];
 //  imageName=[dictionary objectForKey:@"questionImage"];
 // imageURL=@"http://localhost:85/2/";
 // imageURL=[imageURL stringByAppendingString:imageName];

    NSURL *url = [NSURL URLWithString:imageURL];
    NSData *data = [NSData dataWithContentsOfURL:(NSURL *)url];
    UIImage *img = [[UIImage alloc]  initWithData:data];



    cell.lblScoreCurrent.text=[NSString stringWithFormat:@"%d", reloader];

    cell.lblScore.text=@"/30";
    cell.myImageView.image = img;
    cell.SectionTitle.text=[dictionary objectForKey:@"question"];


    [cell.ansBtn1 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];
    [cell.ansBtn2 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];
    [cell.ansBtn3 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];
    [cell.ansBtn4 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];

    cell.ansBtn1.titleLabel.lineBreakMode = UILineBreakModeWordWrap;
    cell.ansBtn2.titleLabel.lineBreakMode = UILineBreakModeWordWrap;
    cell.ansBtn3.titleLabel.lineBreakMode = UILineBreakModeWordWrap;
    cell.ansBtn4.titleLabel.lineBreakMode = UILineBreakModeWordWrap;



    cell.ansBtn1.titleLabel.textAlignment = UITextAlignmentCenter;
    cell.ansBtn2.titleLabel.textAlignment = UITextAlignmentCenter;
    cell.ansBtn3.titleLabel.textAlignment = UITextAlignmentCenter;
    cell.ansBtn4.titleLabel.textAlignment = UITextAlignmentCenter;


    [cell.ansBtn1 setTitle:[dictionary objectForKey:@"option1"] forState:UIControlStateNormal];
    [cell.ansBtn2 setTitle:[dictionary objectForKey:@"option2"] forState:UIControlStateNormal];
    [cell.ansBtn3 setTitle:[dictionary objectForKey:@"option3"] forState:UIControlStateNormal];
    [cell.ansBtn4 setTitle:[dictionary objectForKey:@"option4"] forState:UIControlStateNormal];


    [cell.ansBtn1 addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
    [cell.ansBtn2 addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
    [cell.ansBtn3 addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
    [cell.ansBtn4 addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];

    [cell.ansBtn1 addTarget:self action:@selector(btnActionUp:) forControlEvents:UIControlEventTouchDown];

    //cell.ansBtn1.showsTouchWhenHighlighted=TRUE;
    cell.ansBtn2.showsTouchWhenHighlighted=TRUE;
    cell.ansBtn3.showsTouchWhenHighlighted=TRUE;
    cell.ansBtn4.showsTouchWhenHighlighted=TRUE;



}


return cell;

}

Answer 1

我仍然不完全理解你的问题..如果你想要一个普通的按钮图像，另一个当用户触摸按钮时，你可以在创建按钮时直接给它们..不需要在按钮时更改图像点击..

[cell.ansBtn1 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];
[cell.ansBtn1 setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState: UIControlStateHighlighted];
[cell.ansBtn2 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];
[cell.ansBtn2 setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState: UIControlStateHighlighted];
[cell.ansBtn3 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];
[cell.ansBtn3 setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState: UIControlStateHighlighted];
[cell.ansBtn4 setBackgroundImage:[UIImage imageNamed:@"option.png"] forState: UIControlStateNormal];
[cell.ansBtn4 setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState: UIControlStateHighlighted];

由于您使用了按钮的突出显示状态，我认为只有当用户手上的按钮时才想要绿色图像（即当用户释放按键时更改为正常图像..）。在这种情况下，上面的代码将起作用。

但是如果你希望按钮图像在用户发布后保持绿色，那么你应该使用UIButton的selected（UIControlStateSelected）属性..

编辑：看到评论后..

在这种情况下，当按钮alloc和init只给出正常状态图像..

[cell.ansBtn setBackgroundImage:[UIImage imageNamed:@"option.png" forState:UIControlStateNormal]];

并点击按钮。

-(void)optionButtonClicked:(UIButton*)sender{
   if(correct){
     // green image..
     [sender setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState:UIControlStateSelected];
   }else{//red image
     [sender setBackgroundImage:[UIImage imageNamed:@"option_red.png"] forState:UIControlStateSelected];
   }
   sender.selected = true;
}

第二次修改：看到编辑后的问题

首先，不要比较像这样的两个字符串..

 if(str==[dictionary objectForKey:@"option1"])

而是使用compare（）函数或isEqualToString（）函数进行比较..

第二件事，你在btnAction函数中使用“ cell ”。我不能相信它在编译时没有显示“ cell is unclared ”错误。 第三，纠正以上两个错误。 第四，纠正错误后尝试使用断点调试代码。你已经试过了吗？在btnAction函数中放置一个断点，看看它是否正在按照你想要的方式执行。然后用你的观察更新这个问题。目前，你的代码中有很多错误，所以我不知道哪一个导致了什么..对我来说，这段代码根本不应该编译..

第三编辑：只是一个事后的想法 试试这个..

-(void) btnAction:(id) sender {
   ((UIButton*)sender).selected = FALSE; 
    NSString *str =((UIButton*)sender).titleLabel.text;
    NSLog(@"%@",str);
    NSLog(@"%@",[dictionary objectForKey:@"option3"]);
    correctAns=[dictionary objectForKey:@"answer"];
    if([str isEqualToString:([dictionary objectForKey:@"option1"])]){
       selectedAns=@"1";
       If ([selectedAns compare:correctAns]==NSOrderedSame) {
          NSLog(@"this is correct");
          [((UIButton*)sender) setBackgroundImage:[UIImage imageNamed:@"option_green.png"] forState:UIControlStateSelected];
          countCorrect++;
        //  cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect]; 

        }else {
           [((UIButton*)sender) setBackgroundImage:[UIImage imageNamed:@"option_red.png"] forState:UIControlStateSelected];
           cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect];
         }
         ((UIButton*)sender).selected = true;
    }
}

第四次编辑：还有一次事后的想法

-(void) btnAction:(id) sender {
    NSString *str =((UIButton*)sender).titleLabel.text;
    NSLog(@"%@",str);
    NSLog(@"%@",[dictionary objectForKey:@"option3"]);
    correctAns=[dictionary objectForKey:@"answer"];
    if([str isEqualToString:([dictionary objectForKey:@"option1"])]){
       selectedAns=@"1";
       If ([selectedAns compare:correctAns]==NSOrderedSame) {
          NSLog(@"this is correct");
          [((UIButton*)sender) setImage:[UIImage imageNamed:@"option_green.png"] forState:UIControlStateNormal];
          countCorrect++;
        //  cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect]; 

        }else {
           [((UIButton*)sender) setImage:[UIImage imageNamed:@"option_red.png"] forState:UIControlStateNormal];
           cell.lblRating.text=[NSString stringWithFormat:@"%i", countCorrect];
         }
    }
}