Code-Along: Parrot

Objectives

1. Create variables.
2. Use NSLog() to print a formatted string to the console.
3. Change the case of a string with the uppercaseString method.
4. Copy a string with the stringWithString: method.
5. Concatenate strings with the stringByAppendingString: method.
6. Concatenate an interpolated string with the stringByAppendingFormat: method.
7. Create a new interpolated string with the stringWithFormat: method.

Instructions

This code-along lab will walk you through creating, manipulating, and concatenating (combining) strings while printing them with NSLog().

Open the objc-parrot.xcodeproj file ($ open objc-parrot.xcodeproj) and navigate to the FISAppDelegate.m implementation file. You'll enter all of your code in the application:didFinishLaunchingWithOptions: method body before the return YES line.

Top-tip: If you wish to play around with Objective-C code snippets, this location in a blank program (or one of these early labs that we're supplying to you) is the best option for a "playground". Objective-C is not accurately supported by any REPL or by playgrounds like many other programming languages including Swift. It takes a full Xcode project to run code snippets.

Code-Along I: "Squawk!"

A. NSLog() and the String Literal

1. Print the string @"Squawk!" to the console by placing it directly inside an NSLog():

• NSLog(@"Squawk!");
• Run the program with ⌘``R, this will print Squawk!.

2. Print the string @"Squawk!" by submitting it to an NSLog() as an argument for a format string with one specifier:

• NSLog(@"%@", @"Squawk!");
• Run the program with ⌘``R, this will print another Squawk!.

3. Copy the line above, but move the exclamation point (!) from the argument string into the format string:

• NSLog(@"%@!", @"Squawk");
• Run the program with ⌘``R, this will print a third Squawk!.

4. Copy the line above, but add a call of the uppercaseString method on the argument string @"Squawk" so the returned (uppercased) string is interpolated into the NSLog()'s format string:

• NSLog(@"%@!", [@"Squawk" uppercaseString]);
• Run the program with ⌘``R, this will print SQUAWK!.

B. NSString Variable

1. Create an NSString variable called squawk and set it equal to a string literal @"squawk" in all lowercase, then submit it to an NSLog() as format argument:

• NSString *squawk = @"squawk";
• NSLog(@"%@", squawk);
• Run the program with ⌘``R, this will print squawk.

2. Now, set the squawk string variable equal to a call of the uppercaseString method on itself, and print it again:

• squawk = [squawk uppercaseString];
• NSLog(@"%@", squawk);
• Run the program with ⌘``R, this will print SQUAWK.

3. Now, add an ! to squawk by setting it equal to a call of stringByAppendingString: on itself, the print it again:

• squawk = [squawk stringByAppendingString:@"!"];
• NSLog(@"%@", squawk);
• Run the program with ⌘``R, this will print SQUAWK!.

At the end of this section your console should print out:

Squawk!
Squawk!
Squawk!
SQUAWK!
squawk
SQUAWK
SQUAWK!

Code-Along II: "Wind in yer sails!"

A. Interpolate multiple strings into an NSLog()

1. Create four NSString variables; wind, inString, yer, and sails; and set them equal to, respectively, @"Wind", @"in", @"yer", and @"sails":

• NSString *wind = @"Wind";
• NSString *inString = @"in";
• NSString *yer = @"yer";
• NSString *sails = @"sails";

2. Print the four strings using a format string with four specifiers separated by a space, and ending with an exclamation point (!):

• NSLog(@"%@ %@ %@ %@!", wind, inString, yer, sails);
• Run the program with ⌘``R, this will print Wind in yer sails!.

B. Interpolate multiple strings into a string variable

1. Create a new NSString variable called windInYerSails and use it to capture the return of calling stringWithFormat: on NSString. Submit to the method call a format string and format arguments identical to the NSLog() above:

• NSString *windInYerSails = [NSString stringWithFormat:@"%@ %@ %@ %@!", wind, inString, yer, sails];

2. Print windInYerSails to the console:

• NSLog(@"%@", windInYerSails);
• Run the program with ⌘``R, this will print another Wind in yer sails!.

C. Build a string by concatenating substrings

1. Print the wind string by itself:

• NSLog(@"%@", wind);
• Run the program with ⌘``R, this will print Wind.

2. Reuse windInYerSails to capture a call of the stringWithString: method on NSString with wind supplied as the argument string, the print windInYerSails:

• windInYerSails = [NSString stringWithString:wind];
• NSLog(@"%@", windInYerSails);
• Run the program with ⌘``R, this will print another Wind.

3. Call the stringByAppendingString: method on windInYerSails with a string literal containing a space (@" ") as the argument:

• windInYerSails = [windInYerSails stringByAppendingString:@" "];
  • NSLog(@"%@", windInYerSails);

4. Call the stringByAppendingString: method on windInYerSails a second time but with inString submitted as the argument, then print windInYerSails:

• windInYerSails = [windInYerSails stringByAppendingString:inString];
• NSLog(@"%@", windInYerSails);
• Run the program with ⌘``R, this will print Wind in.

5. Call the stringByAppendingFormat: method on windInYerSails with a format string containing a space and one format specifier and the yer string as the format argument, then print windInYerSails:

• windInYerSails = [windInYerSails stringByAppendingFormat:@" %@", yer];
• NSLog(@"%@", windInYerSails);
• Run the program with ⌘``R, this will print Wind in yer.

6. Call the stringByAppendingFormat: method on windInYerSails again but now with a format string containing a space, one format specifier, and an exclamation point (!) and the sails string as the format argument, then print windInYerSails again:

• windInYerSails = [windInYerSails stringByAppendingFormat:@" %@!", sails];
• NSLog(@"%@", windInYerSails);
• Run the program with ⌘``R, this will print Wind in yer sails!.

At the end of this section your console should also print:

Wind in yer sails!
Wind in yer sails!
Wind
Wind
Wind in
Wind in yer
Wind in yer sails!

Mostly we figure that means "yes".

Code-Along III: Iago Is Molting

A.

1. Create five new NSString variables; look, at, me, im, and molting; and set them equal to, respectively; @"look", @"at", @"me", @"i'm", and @"molting".

• NSString *look = @"look";
• NSString *at = @"at";
• NSString *me = @"me";
• NSString *im = @"i'm";
• NSString *molting = @"molting";

2. Now print the five strings using an NSLog() with no characters other than the five required format specifiers:

• NSLog(@"%@%@%@%@%@", look, at, me, im, molting);
• Run the program with ⌘``R, this will print lookatmei'mmolting.

3. Now print the five strings again but insert a space between each specifier:

• NSLog(@"%@ %@ %@ %@ %@", look, at, me, im, molting);
• Run the program with ⌘``R, this will print look at me i'm molting.

4. Now print the five strings again but with a comma (,) after the third format specifier and an exclamation point (!) after the fifth format specifier:

• NSLog(@"%@ %@ %@, %@ %@!", look, at, me, im, molting);
• Run the program with ⌘``R, this will print look at me, i'm molting!.

5. Lastly, print the five strings again, but call the uppercaseString method on each of them within the NSLog() itself:
   • NSLog(@"%@ %@ %@, %@ %@!", [look uppercaseString], [at uppercaseString], [me uppercaseString], [im uppercaseString], [molting uppercaseString]);

• Run the program with ⌘``R, this will print LOOK AT ME, I'M MOLTING!.

B.

1. Create a new NSString variable called lookAt and use it to capture the return of calling the stringByAppendingFormat: method on the look string with a format string that has one space and one format specifier and the at string as the format argument, then print lookAt:

• NSString *lookAt = [look stringByAppendingFormat:@" %@", at];
• NSLog(@"%@", lookAt);
• Run the program with ⌘``R, this will print look at.

2. Create a new NSString variable called lookAtMe and use to capture the return of calling the stringByAppendingFormat: method on the lookAt string with a format string that has one space and one format specifier and the me string as the format argument, then print lookAtMe:

• NSString *lookAtMe = [lookAt stringByAppendingFormat:@" %@", me];
• NSLog(@"%@", lookAtMe);
• Run the program with ⌘``R, this will print look at me.

3. Use lookAtMe to capture the return of calling uppercaseString on lookAtMe (itself), then print lookAtMe:

• lookAtMe = [lookAtMe uppercaseString];
• NSLog(@"%@", lookAtMe);
• Run the program with ⌘``R, this will print LOOK AT ME.

4. Create a new NSString variable called imMolting and set it a call on NSString of the stringWithFormat: method supplied with a format string with two format specifiers separated by a space and the im string and molting strings as the format arguments, then print imMolting:

• NSString *imMolting = [NSString stringWithFormat:@"%@ %@", im, molting];
• NSLog(@"%@", imMolting);
• Run the program with ⌘``R, this will print i'm molting.

5. Use imMolting to capture the return of calling uppercaseString on imMolting (itself), then print imMolting:

• imMolting = [imMolting uppercaseString];
• NSLog(@"%@", imMolting);
• Run the program with ⌘``R, this will print I'M MOLTING.

6. Create a new NSString variable called lookAtMeImMolting and use to capture the return of calling stringByAppendingFormat: on lookAtMe. Supply the format argument with a format string containing a comma (,), a space, one format specifier, and an exclamation point (!) and imMolting as the format argument, the print lookAtMeImMolting:

• NSString *lookAtMeImMolting = [lookAtMe stringByAppendingFormat:@", %@!", imMolting];
• NSLog(@"%@", lookAtMeImMolting);
• Run the program with ⌘``R, this will print LOOK AT ME, I'M MOLTING!.

C.

1. Create a new NSString variable called iagoShout and set it equal to a call on NSString of the stringWithFormat: method with a format string with five format specifiers matching the last NSLog() from part A, and the five word strings as the format arguments:

• NSString *iagoShout = [NSString stringWithFormat:@"%@ %@ %@, %@ %@!", look, at, me, im, molting];
• NSLog(@"%@", iagoShout);
• Run the program with ⌘``R, this will print look at me, i'm molting!.

2. Now, print a call of uppercaseString on iagoShout:

• NSLog(@"%@", [iagoShout uppercaseString]);
• Run the program with ⌘``R, this will print LOOK AT ME, I'M MOLTING!.

3. Use iagoShout to capture the return of calling uppercaseString on iagoShout (itself), then print iagoShout:

• iagoShout = [iagoShout uppercaseString];
• NSLog(@"%@", iagoShout);
• Run the program with ⌘``R, this will print another LOOK AT ME, I'M MOLTING!.

At the end of this code-along, your console should print out:

lookatmei'mmolting
look at me i'm molting
look at me, i'm molting!
LOOK AT ME, I'M MOLTING!
look at
look at me
LOOK AT ME
i'm molting
I'M MOLTING
LOOK AT ME, I'M MOLTING!
look at me, i'm molting!
LOOK AT ME, I'M MOLTING!
LOOK AT ME, I'M MOLTING!

View Code-Along: Parrot on Learn.co and start learning to code for free.

View Code-Along: Parrot on Learn.co and start learning to code for free.

View Code-Along: Parrot on Learn.co and start learning to code for free.