How do I choose between multiple UILabels by touch? - iphone

Question

I have 2 UIButtons setup(+/-) when tapped, the number changes by one within a UILabel. What do I need to do to have multiple UILabels and when one is touched I can change its current value with the UIButton(+/-)?

Answer 1

Have a variable that you use as the active label, then add a gesture recognizer to both the UIlabels to capture taps:
label.userInteractionEnabled = YES;
UIGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapRecieved:)];
[label addGestureRecognizer:tap];
[tap release];
//repeat for each additional label
Then in your tapReceived method, swap out the active label
-(void) tapRecieved:(UITapGestureRecognizer *)tap{
currentLabel = (UILabel *) tap.view;
}
Then in the method that you capture clicks to the +/- button, write to currentLabel
Edit: A quick and dirty implementation of your problem. In interface builder I made 2 labels and a button and hooked them up. When you tap a label, it becomes the currentLabel and when you tap the button, whichever label you chose is incremented by 1. Hope it helps.
.h
#import <UIKit/UIKit.h>
#interface junkViewController : UIViewController {
UILabel *label;
UILabel *label2;
UILabel *currentLabel;
int label1Value;
int label2Value;
}
#property (nonatomic, retain) IBOutlet UILabel *label;
#property (nonatomic, retain) IBOutlet UILabel *label2;
- (IBAction)buttonTap:(id)sender;
#end
.m
#import "junkViewController.h"
#implementation junkViewController
#synthesize label;
#synthesize label2;
- (void)dealloc
{
[label release];
[label2 release];
[super dealloc];
}
- (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.
}
#pragma mark - View lifecycle
/*
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
[super viewDidLoad];
}
*/
-(void) tapRecieved:(UITapGestureRecognizer *)tap{
currentLabel = (UILabel *)tap.view;
NSLog(#"tap %#",tap.view);
}
-(void) viewDidLoad{
currentLabel = label;
label.text = [NSString stringWithFormat:#"%d",label1Value];
label2.text = [NSString stringWithFormat:#"%d",label2Value];
label.userInteractionEnabled = YES;
UIGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapRecieved:)];
[label addGestureRecognizer:tap];
[tap release];
tap = nil;
tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapRecieved:)];
label2.userInteractionEnabled = YES;
[label2 addGestureRecognizer:tap];
[tap release];
}
- (void)viewDidUnload
{
[self setLabel:nil];
[self setLabel2:nil];
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
- (IBAction)buttonTap:(id)sender {
int value = [currentLabel.text intValue] + 1;
currentLabel.text = [NSString stringWithFormat:#"%d",value];
}
#end

Answer 2

I had to do something similar recently for a dynamically created menu in my app. This worked well:
In the menu creation method:
#define NAV_WIDTH 220
#define NAV_HEIGHT 220
#define NAV_TOP_HEIGHT 16
#define NAV_ITEM_HEIGHT 30
#define NAV_BOTTOM_HEIGHT 24
#define NAV_LABEL_MARGIN 20
[navPage setFrame: CGRectMake(navLeftCorner, navTopCorner, NAV_WIDTH, NAV_HEIGHT)];
NSArray *menuTitles = [[NSArray alloc] initWithObjects: #"One", #"Two", #"Three", #"Four", nil];
int tag = 1;
double labelTop = NAV_TOP_HEIGHT;
for (NSString *title in menuTitles) {
UILabel *itemLabel = [[UILabel alloc] initWithFrame: CGRectMake(NAV_LABEL_MARGIN, labelTop, NAV_WIDTH - (NAV_LABEL_MARGIN * 2), NAV_ITEM_HEIGHT)];
[itemLabel setUserInteractionEnabled: YES];
UITapGestureRecognizer *menuTap = [[UITapGestureRecognizer alloc] initWithTarget: self action: #selector(menuTapped:)];
[itemLabel addGestureRecognizer: menuTap];
[itemLabel setText: title];
[itemLabel setTag: tag];
[navPage addSubview: itemLabel];
labelTop += NAV_ITEM_HEIGHT;
tag++;
}
. . . which calls this when tapped:
- (void) menuTapped: (UITapGestureRecognizer *)tap
{
UILabel *currentLabel = (UILabel *) tap.view;
int index = (currentLabel.tag - 1);
/* Do stuff based on the tag index */
}
NOTE: This is the ARC-compliant way; add [itemLabel release] after adding to the subview if you're not using ARC.