Control Statements and Loops in Objective-C

Part of the Objective-C For Dummies Cheat Sheet

In programming, as in life, you have to make decisions and act on them. Objective-C provides control statements and loops to help your program take action. You may want to repeat a set of instructions based on some condition or state, for example, or even change the program execution sequence. Here is the basic syntax for Objective-C control statements and loops.

if else

if (condition) {
  statement(s) if the condition is true;
  }
else {
  statement(s) if the condition is not true;
  }

for

for (counter; condition; update counter) {
  statement(s) to execute while the condition is true;
  }

for in

for (Type newVariable in expression ) {
  statement(s); 
  }

or

Type existingVariable ;
for (existingVariable in expression) {
  statement(s);
  }

Expression is an object that conforms to the NSFastEnumeration protocol.

  • An NSArray and NSSet enumeration is over content.

  • An NSDictionary enumeration is over keys.

  • An NSManagedObjectModel enumeration is over entities.

while

while (condition) { 
  statement(s) to execute while the condition is true 
  } 

do while

do {
  statement(s) to execute while the condition is true 
  } while (condition);

Jump statements

return ;
Stop execution and returns to the calling function.
break;
Leave a loop.
continue;
Skip the rest of the loop and start the next iteration.
goto labelName;
...
labelName: 
An absolute jump to another point in the program (don’t use it).
exit();
Terminates your program with an exit code.
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