iOS - passing arguments in action:@selector()

问题

I'm adding a button to a UITableViewCell programmatically. The method to be run when the button is pressed is - (void) quantityDown:(id)sender rowNumber:(int)rowNum, where rowNum is the row that the button appears in.

When adding the target to the button, Xcode autocompletes the following:

[buttonDown addTarget:self action:@selector(quantityDown:rowNumber:) forControlEvents:UIControlEventTouchUpInside];

But no matter what I try, I cannot pass the row number into the method. I assumed the pertinent portion of code would look like

action:@selector(quantityDown:rowNumber:indexPath.row)

but that doesn't do the trick. I've seen other stuff like

action:@selector(quantityDown:)rowNumber:indexPath.row

and

action:@selector(quantityDown:rowNumber:)withObject:@"first" withObject:@"Second"

But neither work. I don't need to pass a first argument, just the row number. I've also tried defining the method like - (void) quantityDown:(int)rowNum and then writing the selector like:

action:@selector(quantityDown:indexPath.row)

but that also doesn't work.

Thoughts?

Thanks in advance.

回答1:

Why don't you make a Custom UIButton class and have the object as property?

See below.

"MyButton.h"

@interface MyButton : UIButton
@property(nonatomic, strong)MyClass *obj;
@end

"MyButton.m"

#import "MyButton.h"

@implementation MyButton

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

@end

Now assign MyButton class to your actual button in the cell/ or initialize the custom button instead of normal UIButton class and assign the object directly.

And in your IBAction where sender=MyButton

- (void) quantityDown:(id)sender{
   MyButton *btn  = (MyButton *)sender;
   //You get the object directly
   btn.obj;
}

Doing it this way you can actually access as many properties you want easily. And its useful in other implementations too.

Hope it helps.

回答2:

Button can carry only one input so keep your sender and rowNum same so that it can be handled easily In cell for row method.

UIButton *b = [UIButton buttonWithType:UIButtonTypeContactAdd];
b.tag = indexPath.row;
[b addTarget:self action:@selector(quantityDown:) forControlEvents:UIControlEventTouchUpInside];

Your method

 - (void)quantityDown:(id)sender  
    {    
       NSLog(@"%d", sender.tag);  
    }

hope this will help...

回答3:

Set each button tag as indexPath.row. Then just declare the function:

- (void)quantityDown:(id)sender

In that method do this:

UIButton *btn = (UIButton *)sender;

Add target like this:

[buttonDown addTarget:self action:@selector(quantityDown:) forControlEvents:UIControlEventTouchUpInside];

From btn.tag you can get the row number. Hope this helps. :)

来源：https://stackoverflow.com/questions/22827259/ios-passing-arguments-in-actionselector

标签

ios

objective-c

methods

action

selector