Increment NSDate for use in for loop [closed] - ios

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I am looking for a way to write a for loop that iterates over an NSDate. Each loop should increment the NSDate by 10 seconds.
I want to have 2 timestamps. Say timestamp A is Midnight Monday and timestamp B is Midnight Tuesday.
What I then want is some code to say for A to B incrementing at 10 second intervals between the two points in time, use the timestamp at current position, and the timestamp at the last position, so I can run a query based on the intervals.
Would someone be so good as to show me how I would do this?
Many thanks

Answer 1

A for loop needs three parts, an initialisation, a compare, and an increment. It could look like this:
for (NSDate *date = startDate; // initialisation
[date compare:endDate] == NSOrderedAscending; // compare
date = [date dateByAddingTimeInterval:10]) // increment
{
// do something with date here, eg:
NSDate *rangeStart = date;
NSDate *rangeEnd = [date dateByAddingTimeInterval:10];
[runQuery begin:rangeStart end:rangeEnd];
}
You might prefer to refactor to use a while loop so that the dateByAddingTimeInterval doesn't need to be repeated.
This is the same structure as a normal for loop:
for (int i = 0; // initialisation
i < 10; // compare
i++) // increment
{
// do something with i here
}

Answer 2

It sounds like you may want to look into NSTimer's timerWithTimeInterval. The interface looks like this:
+ (NSTimer *)timerWithTimeInterval:(NSTimeInterval)seconds target:(id)target selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)repeats
and then you can start one ten seconds later using:
initWithFireDate:interval:target:selector:userInfo:repeats:
You can sign up for a call that is sent every seconds as shown below:
// SomeClass.m
#import "SomeClass.h"
#interface ()
#property (nonatomic, strong) NSTimer timer1;
#property (nonatomic, strong) NSTimer timer2;
#end
#implementation SomeClass
- (id)init
{
self = [super init];
if (self) {
NSDate* date = [[NSDate date] dateByAddingTimeInterval:10];
self.timer1 = [NSTimer timerWithTimeInterval:10 target:self selector:#selector(timerFireMethod:) userInfo:nil repeats:YES];
self.timer2 = [[NSTimer alloc] initWithFireDate:date interval:10 target:self selector:#selector(timerFireMethod:) userInfo:nil repeats:YES];
}
return self;
}
- (void)timerFireMethod:(NSTimer *)timer
{
if (timer == self.timer1) {
NSLog(#"timer1 fired");
}
}
#end