はてなブックマーク

#import "SingletonObject.h" static NSMutableDictionary *cls_varietySingletons = nil; @implementation SingletonObject + (void)initialize { static dispatch_once_t once; dispatch_once(&once, ^ { cls_varietySingletons = [NSMutableDictionary new]; }); } #pragma mark - singleton process + (instancetype)sharedInstance { @synchronized (self) { id storedSingleton = cls_varietySingletons[NSStringFromClass(s

#import <Foundation/Foundation.h> typedef id (^ArithmeticOperator)(id, id); ArithmeticOperator add, subtract, multiply, divide; @interface NSNumber (Arithmetic) - (NSNumber *)numberByOperator:(ArithmeticOperator)opr rightOperand:(NSNumber *)rightOp; @end #import "NSNumber+Arithmetic.h" ArithmeticOperator add = ^id(id op1, id op2) { return [op1 decimalNumberByAdding:op2]; }; ArithmeticOperator subt