Program Crash when I click a switch ???

Question

Here is my old question Link

I ask a question before,But I put the answer in my code It can compiler without error

But when I click the switch ，the program crash

I just want to click the switch ,than return which row I click

Here is my code

First I create a LightTableViewController.h/.m

Than I create LightCell0.h/.m

in LightCell0.h

@interface LightCell0 : UITableViewCell { 
 UILabel     *lightLocation;
 UIImageView *lightImageView;
 UISwitch    *lightSwitch;   
}

@property(nonatomic,retain) UILabel *lightLocation;
@property(nonatomic,retain) UIImageView *lightImageView;
@property(nonatomic,retain) UISwitch *lightSwitch;

- (void)switchlightswitch:(id)sender;

I need each cell will be an image ,Textlabel ,switch inside

In LightCell.m

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
 if ((self = [super initWithStyle:style reuseIdentifier:reuseIdentifier])) {
  lightLocation = [[UILabel alloc]init];
  lightLocation.textAlignment = UITextAlignmentLeft;
  lightLocation.font = [UIFont boldSystemFontOfSize:20];
  lightLocation.backgroundColor = [UIColor blackColor];
  lightLocation.textColor =[UIColor whiteColor];

  lightImageView = [[UIImageView alloc]init];

  lightSwitch = [[UISwitch alloc]init];

  [self.contentView addSubview:lightLocation];
  [self.contentView addSubview:lightImageView];
  [self.contentView addSubview:lightSwitch];

  [lightSwitch addTarget:self action:@selector(switchlightswitch:) forControlEvents:UIControlEventValueChanged];

  // Initialization code

    }
    return self;
}

- (void)switchlightswitch:(id)sender{

 if (lightSwitch.on){
  lightImageView.image = [UIImage imageNamed:@"lightOn.png"];
 }
 else {
  lightImageView.image = [UIImage imageNamed:@"lightOff.png"]; 

} }

- (void)layoutSubviews {

 [super layoutSubviews];
 CGRect contentRect = self.contentView.bounds;
 CGFloat boundsX = contentRect.origin.x;
 CGRect frame;
 frame = CGRectMake(boundsX+10 ,0, 44, 44);
 lightImageView.frame = frame;
 frame = CGRectMake(boundsX+60 ,3, 150, 44);
 lightLocation.frame = frame;
 frame = CGRectMake(boundsX+220, 10,0,0);
 lightSwitch.frame = frame ;

}

So far,the program can response when i change the switch status ,it will also change the image.

but if I put this code in ,i can compiler ,than crash if I touch any switch

[lightSwitch addTarget:self action:@selector(switchToggled:) forControlEvents:UIControlEventValueChanged];

and give a void

- (void)switchToggled:(id)sender {
 UISwitch *theSwitch = (UISwitch *)sender;
    UITableViewCell *cell = (UITableViewCell *)theSwitch.superview;
    UITableView *tableView = (UITableView *)cell.superview;
    NSIndexPath *indexPath = [tableView indexPathForCell:cell];
    if(theSwitch.on) {
  NSLog(@"You Switch On the NodeID:%i ",indexPath.row);
    }
    else {
  NSLog(@"You Switch Off the NodeID:%i ",indexPath.row);
    }
}

the crash message is "Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[LightCell0 indexPathForCell:]: unrecognized selector sent to instance"

does anyone knows what's going on with my code ?

Answer 1

From the error message, I suspect your cast is wrong:

UITableViewCell *cell = (UITableViewCell *)theSwitch.superview;
UITableView *tableView = (UITableView *)cell.superview;

Are you sure that the superview of theSwitch is a UITableViewCell and the super view of the cell is the UITableView. The crash tell you that the tableView object that you respect is a LightCell0 object

Answer 2

For getting the status of the switch, you are using "yourSwitch.on", which I don't think is correct. Chang it to [yourSwitch isOn] and test your app. I see 2 statements in your code where you are checking the state of a switch. Change them and try.

Answer 3

I have found the answer! theSwitch.superview actually returns the contentView inside UITableViewCell. So you should change to: UITableViewCell *cell = (UITableViewCell *)theSwitch.superview.superview;