Blocks cheat sheet

Blocks.m

/**
 * Blocks cheat sheet
 */

///////////////////////////////////
#pragma mark - block typedef
///////////////////////////////////
typedef void(^Block)();
typedef void(^ConditionalBlock)(BOOL);
typedef NSString*(^BlockThatReturnsString)();
typedef NSString*(^ConditionalBlockThatReturnsString)(BOOL);


///////////////////////////////////
#pragma mark - block as property
///////////////////////////////////
@property(copy)Block theBlock;
@property(copy)void(^block)();
@property(copy)void(^conditionalBlock)(BOOL);
@property(copy)NSString*(^blockThatReturnsString)();
@property(copy)NSString*(^conditionalBlockThatReturnsString)(BOOL);


///////////////////////////////////
#pragma mark - block definition inline
///////////////////////////////////
ReturnType(^block_name)(parmeter, types, here) = ^(parameter, types, here) {};
void(^block)(void) = ^{};    
void(^conditionalBlock)(BOOL shouldWork) = ^(BOOL shouldWork){};
NSString*(^blockThatReturnsString)(void) = ^ NSString* { return @"foo"; }; 

NSString*(^conditionalBlockThatReturnsString)(BOOL shouldWork) = ^ NSString* (BOOL shouldWork){ 
    return shouldWork ? @"foo" : @"bar"; 
};

- (void)runBlocks {
  block();
  conditionalBlock(NO);
  NSString *someString = blockThatReturnsString();
  NSString *conditionalString = conditionalBlockThatReturnsString(NO);
}


///////////////////////////////////
#pragma mark - blocks as return values
///////////////////////////////////
- (void (^)(void))doSomething;
- (void (^)(BOOL))doSomethingConditionally;
- (NSString* (^)(void))returnString;
- (NSString* (^)(BOOL))returnStringConditionally;

- (NSString* (^)(BOOL))returnStringConditionally {
    return ^(BOOL shouldReturn) {
        if (shouldReturn) return @"foo";
        return @"bar";
    }
}
    

///////////////////////////////////
#pragma mark - blocks as arguments
///////////////////////////////////
- (void)doSomethingWithBlock:(void (^)(void))block;
- (void)doSomethingWithBlock:(void (^)(BOOL))conditionalBlock;
- (void)doSomethingWithBlock:(NSString* (^)(void))blockThatReturnsString;
- (void)doSomethingWithBlock:(NSString* (^)(BOOL))conditionalBlockThatReturnsString;