I want to check if the currentUser is the same as the user that created the post in order to display a button that would let the user delete that post.
I figured the best way would be to match the currentUser.objectId with the Post's "user Pointer<_User>".
I'm logging the currentUser's objectId with this code:
PFUser *currentUser = [PFUser currentUser];
NSString *currentUserID = currentUser.objectId;
NSLog(#"%#", currentUserID);
How can I log the Post's user Pointer<_User>?
Thanks.
First thing to do is to query the desired post object and then you can get the user pointer like retrieving the common value:
PFObject *post = ...; // I assume you know how to get your desired object
PFUser *postedUser = post[#"user"]; // user is the column name
I'm new to programming, and I feel a little intimidated posting, and I'm stuck. I don't want a quick fix! Please help me understand this.
I've created a custom method with a name, age, height and gender. It gets called when the NSMutableArray adds custom objects to the array. For some reason I cannot pull said items out of the NSMutableArray. Let's say the age needs to be printed out. I get a error saying...
-[Person componentsSeparatedByString:]: unrecognized selector sent to instance
Person.m
- (id)initWithName:(NSString *)n
age:(int)a
height:(float)h
gender:(char)g
{
self = [super init];
if (self) {
self.name = n;
self.age = a;
self.height = h;
self.gender = g;
}
return self;
}
- (NSString *)description
{
NSString *descriptionString = [[NSString alloc] initWithFormat:#"%#, %d, %.1f, %c",
self.name,
self.age,
self.height,
self.gender];
NSLog(#"Description String: %#", descriptionString);
return descriptionString;
}
When adding objects to the NSMutableArray they get converted to a NSString? How do I get the peoples age without the whole strings name and height in the NSLog?
ViewController.m
[self.people addObject:[[Person alloc] initWithName:#"Jake" age:29 height:73.5 gender:'f']];
[self.people addObject:[[Person alloc] initWithName:#"Jerry" age:24 height:82.3 gender:'m']];
[self.people addObject:[[Person alloc] initWithName:#"Jessica" age:29 height:67.2 gender:'f']];
NSString *mystring1 = [self.people objectAtIndex:0];
NSLog(#"%#", mystring1);
// Works
//NSString *list = #"Norm, 42, 73.2, m";
NSArray *listItems = [self.people[0] componentsSeparatedByString:#", "];
NSLog(#"List Items: %#", listItems[1]);// age
Output
Description String: Jake, 29, 73.5, f
Jake, 29, 73.5, f
-[Person componentsSeparatedByString:]: unrecognized selector sent to instance
Solved:
Notice the extra [ age];
int age = [[self.people objectAtIndex:0]age];
NSLog(#"%d", age);
I think the reason it seems like your object is getting converted to a string is this line,
NSString *mystring1 = [self.people objectAtIndex:0];
You need to specify the property if that is all you want to print
NSString *nameString = [[self.people objectAtIndex:0]name];
You can't perform componentsSeparatedByString on your Person object since it's not a string and doesn't have that method. (NSMutableArray objects are not automatically converted to NSStrings.) But to get the age of your Person, should be fairly simple anyway. Just access Person's age property:
int age = self.people[0].age;
NSLog(#"Age: %d", age);
Edit: You can technically use componentsSeparatedByString on your mystring1 NSString, like so:
NSArray *listItems = [mystring1 componentsSeparatedByString:#", "];
NSLog(#"List Items: %#", listItems[1]);// age
But again, I don't see the point of doing this when you can access the Person's age property directly.
The componentsSeparatedByString method is an instance method of NSString class. You can't call it on your Person class in this way.
I don't know why you need that code, if you are trying to access age, then:
NSLog(#"Age %d", self.people[0].age);
is enough. If you are trying to achieve any other thing, then you can get the components like:
NSArray *listItems = [self.people[0].description componentsSeparatedByString:#", "];
NSLog(#"List Items: %#", listItems[1]);// age
One would think this would work; however, I can not call .age on my array.
NSLog(#"Age %d", self.people[0].age);
Gives the following output...
Property 'age' not found on object of type 'id'
One would also think componentsSeparatedByString would work. It doesn't split my string by the comma and gives an error.
-[Person componentsSeparatedByString:]: unrecognized selector sent to instance
Solved READ UP
I think you are getting confused about why when you log the object you are getting a string, but you can't perform any methods on it.
And here is why you think you are getting a string, you've implemented the description property, which comes from the NSObject protocol. When you do a log of an object with a %# parameter you are getting the result of this property, which is a string.
So looking at your code:
NSString *mystring1 = [self.people objectAtIndex:0]; //1
NSLog(#"%#", mystring1); //2
The first thing is that you are getting the first object out of your array. objectAtIndex returns an id, which is a pointer to an NSObject. It is not a strongly typed return. You are allocating it to an NSString which is wrong, because it as actually a person object. But since you aren't calling any NSString methods on it, the compiler is not flagging this incorrect assignment.
The second thing is that you are just getting the result of the description property, as I've already mentioned.
Your edited solution:
int age = [[self.people objectAtIndex:0]age];
Works, but here is why: you are getting the objectAtIndex:0 which returns an id. Then you are sending it the message age. Objective-C is a dynamic language, which means you can send any message to any object (although you get a run-time crash if the object does not implement the method) In this case, your Person object does implement an age method (since it's a public property) so you get an age back.
A different way of doing it:
NSInteger age;
Person *person = self.people.firstObject;
if (person) {
age = person.age;
} else {
age = NSNotFound;
}
Why am I doing it this way?
Firstly, I am getting the firstObject out of the array and putting it into a typed variable. This is safer, as if there is no object at index 0 (i.e. the array is empty) then you won't crash your app. firstObject returns the first object if it exists, on a nil if it doesn't.
Secondly, Only if the person has been correctly extracted from the array, do I assign the age to an NSInteger variable. You should prefer the specific types of NSInteger over int (and CGFloat over float) because they will use the correctly sized variable when running on 32-bit or 64-bit` systems.
Thirdly, if person cannot be created I am assigned the value of NSNotFound to the age. This is a typedef for a very large number, one that you can compare against. Just returning 0 in age is not enough to tell you there was an error. The person could have an age of 0. with this code you can test the age with:
if (age != NSNotFound) {
// This is a valid age, do something with it
} else {
// A person object could not be extracted from the array, this is not a valid age
}
Is this overkill? Not really. When you start writing real, complex apps, this sort of defensive programming will come naturally to you. Arrays can be empty, your data could be incorrectly created, etc. Writing code that gracefully handles these eventualities is the real skill of programming. Unfortunately, It's a bit more long winded, and most tutorials that you find on the web show you the simple, happy path.
I hope this gives you a better idea of what your code is doing and what more you could be doing to write robust code.
I have one value which looks like this "00123-23" ,I have no idea about the datatype to be used to store in the table. So I used Text data type to store this value.But When I try to check this value, the query is saying that there is no such value in my table, but actually there is a value. Here is my query:
NSString *x_accountNo;
x_accountNo=[_substrings objectAtIndex:2]; //x_accountNo=00123-23
NSString *query_newAccount = [NSString stringWithFormat:#"SELECT * FROM MYTABLE WHERE ACCOUNT=%# ",x_accountNo];
BOOL recordExist_newAccount = [self recordExistOrNot_newAccount:query_newAccount];
if (!recordExist_newAccount) {
nslog(#"no data");
}
Everytime I execute this statement, It is giving me no data . Could you please tell me what I am doing wrong here?
You might need to have string inside quotes:
SELECT * FROM MYTABLE WHERE ACCOUNT='%#'
I save a few objects in the _User class in parse, such as displayname, gender, and bio. A simple user profile. I'm having difficulty retrieving them. I tried with many types of queries with no luck. So I figured if you could get the username by doing this:
self.username.text = [NSString stringWithFormat:#"#""%#",[[PFUsercurrentUser]valueForKey:#"username"]];
You should be able to get other objects that are stored in _User right? Well I tryed this to get the display name:
self.name.text = [NSString stringWithFormat:#"%#",[[PFUser currentUser]valueForKey:#"name"]];
And I get (null) printed out on the label, except in the data browser there is a value there. I'm really in need of some assistance this has been a problem that's taking me a while to figure it out. Thanks!
You have mentioned two lines in your code:-
//Have modified this line
In this line valueForKey you are passing #"username"
self.username.text = [NSString stringWithFormat:#"%#",[[PFUser currentUser]valueForKey:#"username"]];
In this line valueForKey you are passing #"name"
self.name.text = [NSString stringWithFormat:#"%#",[[PFUser currentUser]valueForKey:#"name"]];
Now in above two line both are having two separate keys username and name. So just check the valid key like that below if you are not sure which is valid, if below any of line prints value then use that key for setting the value in your label:-
NSLog(#"%#",[[PFUser currentUser]valueForKey:#"username"]);
NSLog(#"%#",[[PFUser currentUser]valueForKey:#"name"]);
I am trying to store a date field from a PFObject into my date type attribute of a Core Data entity.
coreDataObject.createdAt = [object createdAt];
This is the error XCode is returning : property = "updatedAt"; desired type = NSDate; given type = __NSCFString;
Before doing this I was storing the date as a string and parsing that [object createdAt] and everything was working fine, but now it doesn't recognize it as a NSDate.
I've tried casting in but nothing seems to work.
Any idea?
Note, it's this simple:
NSDate *teste = oneParseRow.createdAt;
NSLog(#"teste is %#", ttt);
Note that:
[oneParseRow objectForKey:#"createdAt"];
or anything similar, simply does not work, in any way. You just have to use .createdAt.
Could you verify in the Parse documentation that the createdAt method returns an NSDate? It seems that it is returning a NSString.
Try this code:
id created = [object createdAt]
coreDataObject.createdAt = created;
Put a breakpoint in the first line and within the debugger inspect the type of object that createdAt is returning. If it is not an NSString instead of NSDate you will have to convert it to a NSDate with a NSDateFormatter.