Inherited value from other control

Question

I am new in programming.I have an basic doubt of inheritance.I have a UITableView in ViewController and when I select first row of Tableview.It take me to the Picker page in which only I have to select value from UIPickerViewthats fine now I have to NSLOG selected value of picker in a ViewController in button.this is small problem I am facing.

VIewController.m

- (void)viewDidLoad
 {
 [super viewDidLoad];

tableview =[[UITableView alloc]initWithFrame:CGRectMake(0,0,([UIScreen mainScreen].bounds.size.width),([UIScreen mainScreen].bounds.size.height/2)) style:UITableViewStyleGrouped];
tableview.delegate=self;
tableview.dataSource=self;
[self.view addSubview:tableview];




button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[button addTarget:self action:@selector(pressed) forControlEvents:UIControlEventTouchDown];
[button setTitle:@"START " forState:UIControlStateNormal];
button.frame = CGRectMake(62, 250, 196, 37);
[self.view addSubview:button];



thearray= [[NSArray alloc]initWithObjects:@"A",@"B ",@"C",@"D",@"E" ,nil];



 [super viewDidUnload]; 
}

 -(void)pressed{
  // nslog value..i need here the picker value
   }

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



 - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{


return 5;
}



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


if(indexPath.row==0){

 Picker1 *pick= [[Picker1 alloc] init];


    [self navigationController] pushViewController:pick animated:YES]      
}


 }




 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NS IndexPath *)indexPath  
{  
static NSString *CellIdentifier = @"Cell";  


 UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
 if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier];
}


cell.textLabel.text=[thearray objectAtIndex:indexPath.row];

 return cell;
}

Picker.m

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {

return 1;

}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {

return [list count];

}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {

return [list objectAtIndex:row];

}


- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {

// update label text to show selected option

string=[NSString stringWithFormat:@"%@",[list objectAtIndex:row]];

label.text=string;


[self dismissModalViewControllerAnimated:YES];



 }


- (void)viewDidLoad
{
[super viewDidLoad];

list =[[NSMutableArray alloc]init];
[list addObject:@"A"];
[list addObject:@"B"];
    [list addObject:@"C"];



}

Answer 1

You can use delegates

in picker.m,above @interface section do this

@protocol pickerDelegate <NSObject>

-(void)didFinishPicking:(NSString *)pickedStr;

@end

make property of this protocol

@property(nonatomic,weak)id<pickerDelegate>delegate

and in - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component method, do this

string=[NSString stringWithFormat:@"%@",[list objectAtIndex:row]];



[self.delegate didFinsihPicking:string];

now in viewcontroller.h, in the method

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


 Picker1 *pick= [[Picker1 alloc] init];

[pick setDelegate : self];

and implement the dlegate method in viewcontroler.h

    -(void)didFinishPicking:(NSString *)pickedStr
{
[self setStr:pickedStr]
}

where str is the string variable you need to declare in viewcontroller.h and print this string on button click event

Answer 2

It sounds like you need a delegate for your picker to pass the selected value back to the table view. Define the delegate method at the top of your Picker.h file:

@class Picker;

@protocol PickerDelegate <NSObject>

- (void)picker:(Picker *)thePicker didPickValue:(NSString *)theValue;

@end

Also in your Picker.h file, create a weak connection to the delegate which will be the table view controller:

@property (nonatomic, weak) id <PickerDelegate> delegate;

In your table view controller add the delegate to the header file:

@interface ViewController : UITableViewController <PickerDelegate>

You call the delegate method from your Picker.m and implement it in your ViewController.m:

[self.delegate picker:self didPickValue:[NSString stringWithFormat:@"%@",[list objectAtIndex:row]]];

IMPORTANT: When you create the picker, you must tell it who the delegate is going to be. You are doing this within your table view, so you call:

pick.delegate = self;