iOS UISwitch keep sending message every 4 second - ios

Question

I have a chatting app that has a uiswitch. If the Switch button is on, I want the app to send "hi" continuously every 3 seconds even the app is in background mode. I know that I can use NSTimer, but I don't really know how to implement that in this code(This is my first time to develop iOS app). Please help me with this.
My code is :
// Allocate, initialize, and add the automatic button.
_AutomaticSend = [[UISwitch alloc] initWithFrame:CGRectMake([self width] - 50.0, textAreaY + Center(160.0, textAreaHeight), 50.0, 50.0)];
[_AutomaticSend addTarget:self action:#selector(changeSwitch:) forControlEvents:UIControlEventValueChanged];
and
// Switch action
//NSUInteger counter = 0;
- (void)changeSwitch:(id)sender{
if([sender isOn]){
for (int a=1; a<=300; a++)
{
//[self performSelector:#selector(changeSwitch:) withObject:_textField afterDelay:70.0];
[sender setOn:YES animated:YES];
[_textField setText:#"hi"];
NSString * text = [_textField text];
// Update status.
[[TSNAppContext singleton] updateStatus:text];
// Add the status to the bubble.
[self appendLocalPeerTableViewCellWithMessage:text];
}
// NSLog(#"Switch is ON");
} else{
NSLog(#"Switch is OFF");
}
}
Now, the app is showing all "hi" after all 300 "hi" is ready to show. But I want it to send it one by one continuously.

Answer 1

Define a NSTimer instance and a counter in your view controller:
#property (nonatomic, strong) NSTimer *timer;
#property (nonatomic, assign) NSInteger counter;
Implement the method when timer is fired:
- (void)timerAction:(id)sender {
[_textField setText:#"hi"];
NSString * text = [_textField text];
// Update status.
[[TSNAppContext singleton] updateStatus:text];
// Add the status to the bubble.
[self appendLocalPeerTableViewCellWithMessage:text];
// stop the timer after sending for 300 times
self.counter += 1;
if (self.counter >= 300) {
[self.timer invalidate];
self.timer = nil;
}
}
Starts the timer when switch is on:
- (void)changeSwitch:(id)sender{
if ([sender isOn]) {
self.counter = 0;
self.timer = [NSTimer scheduledTimerWithTimeInterval:3 target:self selector:#selector(timerAction:) userInfo:nil repeats:YES];
} else {
// kill the timer when switch is off
[self.timer invalidate];
self.timer = nil;
}
}
However, you can't make the timer to continue working indefinitely after your app is entering background (with some exceptions: VoIP, GPS applications, etc.). Please refer to the official document Background Execution.

Answer 2

//Nstimer *timer in .h
In your UISwitch Method Write like this
- (void)changeSwitch:(id)sender{
if([sender isOn]){
timer=[NSTimer scheduledTimerWithTimeInterval:2.0
target:self
selector:#selector(targetMethod)
userInfo:nil
repeats:NO];
}
else
{
[timer invalidate];
}
}
targetMethod Like this
-(void)targetMethod
{
[sender setOn:YES animated:YES];
[_textField setText:#"hi"];
NSString * text = [_textField text];
// Update status.
[[TSNAppContext singleton] updateStatus:text];
// Add the status to the bubble.
[self appendLocalPeerTableViewCellWithMessage:text];
}

Answer 3

Use NSTimer: Documentation of NSTimer
Declare property of NSTimer in .h file:
#property (retain,nonatomic) NSTimer *myTimer;
- (void)changeSwitch:(id)sender
{
if([sender isOn]){
myTimer = [NSTimer scheduledTimerWithTimeInterval: 4 target: self
selector: #selector(AddMessage:) userInfo: nil repeats: YES];
} else{
[self.timer invalidate];
}
}
After each 4 second, timer will call the below function:
-(void) AddMessage:(NSTimer*) timer
{
//Add Message
}