Pass and access structures using objective-c

问题

I want to know how to pass structures to another function and subsequently access that structure in the called function. I'm developing for the iPhone and the reason I'm using structs is so that I can eventually pass data as structs to a server being built in C.

Here's the structure:

struct userInfo{
    NSString *firstName;
    NSString *lastName;
    NSString *username;
    NSString *email;
    NSString *ipAddress;
    double latitude;
    double longitude;
};

Here I'm simply fetching some user inputed data along with some CoreLocation data and the iPhone's IP Address:

- (IBAction)joinButton {
    struct userInfo localUser;

    localUser.firstName = firstName.text;
    localUser.lastName = lastName.text;
    localUser.username = username.text;
    localUser.email = emailAddress.text;
    localUser.ipAddress = localIPAddress.text;
    localUser.latitude = currentLocation.coordinate.latitude;
    localUser.longitude = currentLocation.coordinate.longitude;

    [myNetworkConnection registerWithServer:&localUser];
}

function handling the struct:

- (void)registerWithServer:(struct userInfo*)myUser {

    printf("First name is: %s", myUser.firstName);//error when compiling
}

the complier throws this error: request for member 'firstName' in something not a structure or union. Is that struct out of scope when I try to access it in the second function?

回答1:

You are passing in a pointer to a struct. Use the -> operator, not the dot.

myUser->firstName

回答2:

I can't help but think you should really make that a proper objective-C object with properties - more work but then it'll all behave better and live within the NSObject ecosystem.

来源：https://stackoverflow.com/questions/1064500/pass-and-access-structures-using-objective-c

标签

iphone

objective-c

struct

argument-passing