如何在NSMutableArray中存储最多5个对象？

Question

I am creating an array of NSdictionarys and putting that array in NSUserDefaults. I then put the array data in a recently added tableview. I am trying to get it so it would store the 5 most recent objects added to that array. How can I go about this? Below is my code:

- (IBAction)searchButton:(UIButton *)sender {

[_jobDic setObject:_jobField.text forKey:@"jobRecent"];
[_jobDic setObject:_locationField.text forKey:@"locationRecent"];
[_recentJobArray addObject:_jobDic];

[_recentDefaults setObject:_recentJobArray forKey:@"recentJobs"]

[_recentDefaults synchronize];    

}

Answer 1

Assuming you are referring to the _recentJobArray , you could do this:

if (_recentJobArray.count == 5) {
    [_recentJonArray removeObjectAtIndex:0]; // remove oldest
}
[_recentJobArray addObject:_jobDic];

Answer 2

If you keep your array sorted in newest-to-oldest order then maddy's solution will work well. Otherwise you'll need to save a date key/value pair in each dictionary, and then loop through the array looking for the oldest item. The code might look something like this

NSDictionary *oldest;
for (NSDictionary *aJobDict in _recentJobArray)
{
  NSDate *dateOfThisDict = aJobDict[@"date"]; //Assumes each dict has a key @"date"
  if (!oldest || [oldest[@"date"] compare: dateOfThisDict] == NSOrderedDesending)
    oldest = aJobDict;
}
[_recentJobArray removeObject: oldest];
[_recentJobArray addObject: newDict];