An introduction to the Objective-C Language
##What is a computer program? A computer program is a list of instruction given to the computer in a language it can understand. Our language for this class is Objective-C. A great website to learn more about Objective-C is Ry's Objective-C Tutorial
##Objective-C Primitives One of the primary reasons for computer languages is to do useful things with information. Historically, this has meant working with numbers and letters (as they are what humans like us use to get things done). These are also known as variables in a computer program.
###Numbers There are a few ways to represent numbers in Objective-C. Each one has specific uses. We will cover a few of the basics here.
####Integers An integer is a positive or negative number from -4294967295 to 4294967295 (or -2^32 -1 to 2^32 -1). You create an integer named "myInteger" like so.
int myInteger = 32; Use integers to represent what will be reasonably sized numbers.
####Longs An long is a positive or negative number from -9223372036854775807 to 9223372036854775807 (or -2^64 - 1 to 2^64 -1). You create a long named "myLong" like so.
long myLong = 12938348573; Use longs to represent what will be large numbers.
####Floats An long is a positive or negative decimal number of reasonable size (se Ry's for details). You create a float named "myFloat" like so.
float myFloat = 129383.48573; ####Doubles An long is a positive or negative decimal number of large size (se Ry's for details). You create a double named "myDouble" like so.
double myDouble = 1291230383.4823573; ###Strings So, numbers are great, but what if we want to represent words in our code? Representations of alphabetical characters is done using strings. To create a string called "myBasicString" that contains the words "Basic String", write the following:
NSString *myBasicString = @"Basic String";There are, however, other ways to build a string from numbers! Using the variables we made above (or just the numbers!), we can create strings
NSString *myIntString = [[NSString alloc] initWithFormat:@"%d", myInt];
NSString *myFloatString = [[NSString alloc] initWithFormat:@"%f", 123.123];
NSString *myStringString = [[NSString alloc] initWithFormat:@"%@%@ - %d", @"First String", @"Second", 123];