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Code-Along: Parrot

Objectives

  1. Create variables.
  2. Call methods to manipulate strings.
  3. Concatenate strings with methods on NSString and NSMutableString.
  4. Print to the console with NSLog() supplied with interpolated strings.

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 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!"

  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!.
  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.
  1. Now, set the squawk string variable equal to a call of the uppercaseString method on itself:
  • squawk = [squawk capitalizedString];
  1. Then add an ! to squawk by setting it equal to a call of stringByAppendingString on itself:
  • squawk = [squawk stringByAppendingString:@"!"];
  1. Now, print squawk to the console using NSLog():
  • NSLog(@"%@", squawk);
  • Run the program with ⌘``R, this will print Squawk!.

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

Squawk!
squawk
Squawk!

Code-Along II: "Dead men tell no tales!"

  1. Create three NSString variables; deadMen, tell, and noTales; and set them equal to, respectively, @"Dead men", @"tell", and @"no tales":
  • NSString *deadMen = @"Dead men";
  • NSString *tell = @"tell";
  • NSString *noTales = @"no tales";
  1. Use the formatting ability of NSLog() to print these three string concatenated into a regular sentence, with a space between each format specifier and an exclamation point (!) at the end:
  • NSLog(@"%@ %@ %@!", deadMen, tell, noTales);
  • Run the program with ⌘``R, this will print Dead men tell no tales!.
  1. Create a new NSMutableString variable called pirateParrot and set it equal to an +alloc -init of a new NSMutableString:
  • NSMutableString *pirateParrot = [[NSMutableString alloc] init];
  1. Now, append deadMen to pirateParrot by calling the appendString: method on pirateParrot with deadMen supplied as the argument:
  • [pirateParrot appendString:deadMen];
  • Run the program with ⌘``R, this will print Dead men.
  1. Then, append tell and noTales to pirateParrot by calling the appendFormat: method on pirateParrot and supplying a formatted string that includes a space before tell, a space between tell and noTales, and an exclamation point (!) at the end:
  • [pirateParrot appendFormat:@" %@ %@!", tell, noTales];
  • Run the program with ⌘``R, this will print Dead men tell no tales!.

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

Squawk!
squawk
Squawk!
Dead men tell no tales!
Dead men tell no tales!

Code-Along III: Iago Is Molting

  1. Create two new NSString variables called iagoLook and iagoMolting and respectively set them equal to the lowercase strings @"look at me" and @"i'm molting":
  • NSString *iagoLook = @"look at me";
  • NSString *iagoMolting = @"i'm molting";
  1. Print a concatenation of the strings using an NSLog():
  • NSLog(@"%@ %@", iagoLook, iagoMolting);
  • Run the program with ⌘``R, this will print look at me i'm molting.
  1. Make the strings uppercase by setting the strings equal to a call of the uppercaseString method to themselves, then NSLog() the strings again like above:
  • iagoLook = [iagoLook uppercaseString];
  • iagoMolting = [iagoMolting uppercaseString];
  • NSLog(@"%@ %@", iagoLook, iagoMolting);
  • Run the program with ⌘``R, this will print LOOK AT ME I'M MOLTING.
  1. Create a new NSString variable called iagoShout and set it equal a call of NSString's stringWithFormat: method supplied with a format string with two object format specifiers separated by a space and ending with an ! ("exclamation point"), and the arguments iagoLook and iagoMolting, then print iagoShout using an NSLog():
  • NSString *iagoShout = [NSString stringWithFormat:@"%@ %@!", iagoLook, iagoMolting];
  • NSLog(@"%@", iagoShout);
  • Run the program with ⌘``R, this will print LOOK AT ME I'M MOLTING!.

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

Squawk!
squawk
Squawk!
Dead men tell no tales!
Dead men tell no tales!
look at me i'm molting
LOOK AT ME I'M MOLTING!
LOOK AT ME I'M MOLTING!