OC 断言NSAssert

-(id)initWithEntryDate:(NSDate *)theDate{

    NSAssert(theDate!=nil,@"Argument must be non -nil");//当theDate=nil抛出异常

    self = [superinit];

    if (self) {

        entryDate = theDate;

        firstNumber = random()%100+1;

        secondNumber = random()&100+1;

    }

    return  self;

}