I have a function set up in my code like so:
-(IBAction) buttonClicked: (id) sender{
//various expressions here
}
The question is, how can I call this buttonClicked() function from somewhere else in the code, without requiring a user click the button. For example, how can I call it from viewDidLoad()?
Thank you for any help.
If you're calling in the same file, you can use:
[self buttonClicked:self];
Depending on what your method does.
Related
If I have this function for button click
-(IBAction)loginButton:(UIButton *)sender{ }
How can I call this button function from this another method
-(void)increaseAmount {
myNumber = myNumber+0.01;
if (myNumber >= 1) {
[self loginButton:sender];
}
progressViewAuto.progress = myNumber;}
I have tried the above code but getting error that USE OF UNDECLARED IDENTIFIER 'sender'
Simply pass in nil or even self.
And, if you want to be perfectly correct, you can link your UIButton to IBOutlet UIButton* theLoginButton; and then say [self loginButton:theLoginButton];.
But this would only be needed if you actually reference the sender in your loginButton routine, and that's the exception rather than the rule.
You probably just want to send nil, like this:
[self loginButton:nil];
I want to call another method from the updateButtonPressed method.
This is what I tried:
-(IBAction) updateButtonPressed{
[self loadScrollViewWithPage];
}
But the problem is that the loadScrollViewWithPage method has arguments. That method is like this:
- (void)loadScrollViewWithPage:(int)page {
}
How can I call this method?
If I understand correctly, you are wondering how to pass arguments along with messages to objects, is that right? Try:
-(IBAction) updateButtonPressed{
int foo = 4;
[self loadScrollViewWithPage:foo]; // a colon, followed by the argument
}
I suggest you read up on the Objective-C language in general, though.
http://developer.apple.com/library/mac/#documentation/cocoa/conceptual/objectivec/introduction/introobjectivec.html
- (IBAction) updateButtonPressed{
int tempValue=5;
[self loadScrollViewWithPage:tempValue];
}
I was trying to pass a variable of type NSString from a method to another. what I have done is:
-(void)some{
NSString *lat = something
NSString *longt = somethingElse
[self test:lat:longt];
}
and then
- (IBAction)test:(NSString *)lat:(NSString *)longt{
doSomeThing
}
But my problem is that now the IBAction button is activated without my press.
how do I run the method IBAction under my control
you cannot pass arbitrary parameters through an IBAction, you can either pass the control sending the action or nothing:
-(IBAction)action:(id)sender;
or
-(IBAction)action;
The test method should not be an IBAction. Instead do this:
- (void)test:(NSString *)lat:(NSString *)longt{
//doSomeThing
}
-(IBAction)myAction:(id)sender
{
//call test from here
[self some];
}
You should use void as returm type of method not ibaction. If u need it for some action thn call it from there.
use
- (void) test:(NSString *)lat:(NSString *)longt
instead of
- (IBAction)test:(NSString *)lat:(NSString *)longt
I have a method hideButton
-(void) hideButton:(UIButton) *button {
[button setHidden:YES];
}
and I get a "can not use an object as parameter to a method" error.
I want to be able to give the button as a parameter to the method when calling this
[self performSelector:#selector(hideButton:smallestMonster1)
withObject:nil afterDelay:1.0];
How can this be done? as the above attempt doesnt work. I need to be able to give the button as a parameter or at least make the method aware of which button is calling to be hidden after 1 second.
Thanks
You can pass parameter to selector via withObject parameter:
[self performSelector:#selector(hideButton:) withObject:smallestMonster1 afterDelay:1.0];
Note that you can pass at most 1 parameter this way. If you need to pass more parameters you will need to use NSInvocation class for that.
Edit: Correct method declaration:
-(void) hideButton:(UIButton*) button
You must put parameter type inside (). Your hideButton method receives pointer to UIButton, so you should put UIButton* there
How do you add a (id) sender to the following code?
- (IBAction) gobutton: (UIButton *) button5 {
Everything I try fails, any help would be appreciated. Thanks.
EDIT: I need to keep the (UIButton *) button 5 reference in the (IBAction)
If I recall correctly, and if you are using this in the way I think you are,
- (IBAction) gobutton: (id) sender {
if(sender == button5)
//do something...
else
//do something else...
}
Assuming that you specified button5 as a parameter to indicate that this executes in response to button5 being pressed.
Ok, first.... IBAction doesn't really mean anything special except to Interface Builder. Basically:
#define IBAction void
So whenever you see IBAction, think "void". The only reason it's there is as a flag to tell Interface Builder that a method is a valid method to connect control actions to. The Objective-C compiler doesn't need to know about it and so it's defined to void since all "action" methods return void.
Second, action methods also have one argument which could be an object of any number of types. Because of this, action methods are supposed to use type id as the type for their argument. That way they can be passed a pointer to any Objective-C object without causing the compiler to generate a type checking error.
So usually actions should work something like this:
- (IBAction)myAction:(id)sender {
if (sender == self.someButton) {
UIButton *button = (UIButton *)sender;
...
return;
} else if (sender == self.someControl) {
UIControl *control = (UIControl *)sender;
...
return;
}
}
In other words, an id is almost like an untyped pointer like a void * is routinely used in C when some function needs to take a pointer to something of unknown type. sender could be different types of control, so something generic like id is used then sender is cast to something more specific once the code knows what it is.
Anyway, there is absolutely no reason to define something as having a return type of IBAction unless you are going to use that method as a target action in Interface Builder. Having an IBAction in your app delegate seems kind of unusual....
It's not clear what you are trying to do but most actions look like:
- (IBAction) gobutton: (id)sender;
The first parameter to an action is always the sender (you can specify the type and name as appropriate).
If a method is the action for a button, then the first parameter will be the button. If that method is the action for several buttons, then the first parameter will allow you to determine which button was tapped (as Leper describes).
What problem are you actually trying to solve?
There are techniques for passing information to the action method. For example, if you have a button that appears on a table view cell and performs the same action for every cell, then in the action method, you would want to be able to determine which cell's button was tapped.
How can I get the id of the sender before the user touches the control?
Found it! Set a tag and the use viewWithTag.
Can you create a simple structure that contains both the UIButton and the sender and use that?
struct myObject
{
UIButton* button5;
id sender;
}
...or, you could create your own NSObject (probably more cocoa-y):
#instance myObject : NSObject
{
...
}