NSString tests not working while testing if string location is null

Okay I know there are like a thousand questions of this type, but none of those suggestions seem to work so I am forced to make yet another question about this since this is starting to break my b**ls. Now the question and context:

I get a location from the iPhone, but in the case that the location is not available or part of it is not available I reinitialize the string to @"" instead of a ugly @"(null)" because this location I get it uploaded into a server.

This is the allocation of the variables:

        NSString *country = [NSString stringWithFormat:@"%@", placemarkFound.country];
        NSString *postalCode = [NSString stringWithFormat:@"%@", placemarkFound.postalCode];
        NSString *locality = [NSString stringWithFormat:@"%@", placemarkFound.locality];
        NSString *thoroughfare = [NSString stringWithFormat:@"%@", placemarkFound.thoroughfare];
        NSString *subThoroughfare = [NSString stringWithFormat:@"%@", placemarkFound.subThoroughfare];

These are the tests I'm currently making:

        if (country == (id)[NSNull null] || country.length == 0) {
            NSLog(@"Entered first if for (null)");
            country = @"";
            postalCode = @"";
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (postalCode == (id)[NSNull null] || postalCode.length == 0) {
            postalCode = @"";
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (locality == (id)[NSNull null] || locality.length == 0) {
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (thoroughfare == (id)[NSNull null] || thoroughfare.length == 0) {
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (subThoroughfare == (id)[NSNull null] || subThoroughfare.length == 0) {
            subThoroughfare = @"";
        }

Second:

        if (country == @"(null)") {
            NSLog(@"Entered first if for (null)");
            country = @"";
            postalCode = @"";
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (postalCode == @"(null)") {
            postalCode = @"";
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (locality == @"(null)") {
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (thoroughfare == @"(null)") {
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (subThoroughfare == @"(null)") {
            subThoroughfare = @"";
        }

Third:

        if (!country) {
            NSLog(@"Entered first if for (null)");
            country = @"";
            postalCode = @"";
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (!postalCode) {
            postalCode = @"";
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (!locality) {
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (!thoroughfare) {
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (!subThoroughfare) {
            subThoroughfare = @"";
        }

Fourth:

With a class:

static inline BOOL IsEmpty(id 开发者_如何转开发thing) {
return thing == nil
|| ([thing respondsToSelector:@selector(length)]
    && [(NSData *)thing length] == 0)
|| ([thing respondsToSelector:@selector(count)]
    && [(NSArray *)thing count] == 0);
}
        if (IsEmpty(country)) {
            NSLog(@"Entered first if for (null)");
            country = @"";
            postalCode = @"";
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (IsEmpty(postalCode)) {
            postalCode = @"";
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (IsEmpty(locality)) {
            locality = @"";
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (IsEmpty(thoroughfare)) {
            thoroughfare = @"";
            subThoroughfare = @"";
        } else if (IsEmpty(subThoroughfare)) {
            subThoroughfare = @"";
        }

So there are two possibilities, I'm making something horribly wrong or there is a much simpler way to do this. I NSLogged the variables to this output:

Variables before testing, country: (null)
postalCode: (null)

Thank you for your help!!

Instead of country == @"(null)" you need to do: [country isEqual:@"(null)"] (or [country isEqualToString:@"(null)"]). The == operator tests for pointer equality, but you want to check for object value equality.

Edit:

So, the second way is probably the way to go (with the fixed check), but I'd recommend to reverse the check:

if ([@"(null)" isEqual:myStringToTest]) { ... }

This way, the object on which isEqual: is called is guaranteed to be always a valid object (the static object representing @"(null)").

Reading your question more carefully, I’ve noticed you’re using +[NSString stringWithFormat:] when assigning the strings to your variables:

NSString *country = [NSString stringWithFormat:@"%@", placemarkFound.country];
NSString *postalCode = [NSString stringWithFormat:@"%@", placemarkFound.postalCode];
NSString *locality = [NSString stringWithFormat:@"%@", placemarkFound.locality];
NSString *thoroughfare = [NSString stringWithFormat:@"%@", placemarkFound.thoroughfare];
NSString *subThoroughfare = [NSString stringWithFormat:@"%@", placemarkFound.subThoroughfare];

This is the reason why a test like

if (! country)

or

if (country == nil)

doesn’t work: +[NSString stringWithFormat:] always returns a non-nil string. In your particular code, if placemarkFound.country == nil, then your country variable contains a string representation of nil, namely (null).

Since you’ve said you have no particular reason to use +stringWithFormat:, and assuming all properties/struct members are strings, here’s one solution to your problem:

NSString *country = @"";
NSString *postalCode = @"";
NSString *locality = @"";
NSString *thoroughfare = @"";
NSString *subThoroughfare = @"";

if (placemarkFound.country) country = placemarkFound.country;
if (placemarkFound.postalCode) postalCode = placemarkFound.postalCode;
if (placemarkFound.locality) locality = placemarkFound.locality;
if (placemarkFound.thoroughfare) thoroughfare = placemarkFound.thoroughfare;
if (placemarkFound.subThoroughfare) subThoroughfare = placemarkFound.subThoroughfare;

Note that the variables contain an empty string unless their corresponding properties/struct members are different from nil.

There’s a handy shortcut for this situation. Instead of the code above, you can use the following code that employs the ternary conditional operator:

NSString *country = (placemarkFound.country ? : @"");
NSString *postalCode = (placemarkFound.postalCode ? : @"");
NSString *locality = (placemarkFound.locality ? : @"");
NSString *thoroughfare = (placemarkFound.thoroughfare ? : @"");
NSString *subThoroughfare = (placemarkFound.subThoroughfare ? : @"");

Explaining it:

NSString *country = (placemarkFound.country ? : @"");

means the following: if placemarkFound.country is different from nil, assign it to the country variable. Otherwise, assign an empty string to the country variable.

you can use this too... if( (NSNull *)country == [NSNull null] )