1 if

mrHiggieIsMean = NO;

if (mrHiggieIsMean) {
  NSLog(@"Confirmed: he is super mean");
}

2 if else

BOOL mrHiggieIsMean = [mrHiggie areYouMean];

if (mrHiggieIsMean) {
  NSLog(@"Confirmed: he is super mean");
}else{
  NSLog(@"No, actually he‘s really nice");
}

3 if - else if - else

NSNumber *meannessScale = [mrHiggie meannessScale];

if([meannessScale intValue] < 4) {
  NSLog(@"Mr. Higgie is on the nice side");
} else if([meannessScale intValue] < 8) {
  NSLog(@"Mr. Higgie is sorta nice but not really");
} else {
  NSLog(@"Mr. Higgie is definitely mean");
}

4 Equal strings

传递给 isEqualToString: 比较两个NSString，如果相同则会返回TRUE，反之返回FALSE。

可以用在if的条件判断中：

if([myString isEqualToString:otherString]) {
  NSLog(@"Hello from inside the if!");
}

5 switch case

NSInteger day = getDayOfWeek();

switch (day) {
  case 1: {
    NSLog(@"Monday");
    break;
  }
  case 2: {
    NSLog(@"Tuesday");
    break;
  }
  /* snip Wednesday through Saturday */
  case 7: {
    NSLog(@"Sunday");
    break;
  }
}

6 Switch on enums

switch使用的闪光点在与枚举结合使用。

typedef NS_ENUM(NSInteger, DayOfWeek) {
    DayOfWeekMonday = 1,
    DayOfWeekTuesday = 2,
    DayOfWeekWednesday = 3,
    DayOfWeekThursday = 4,
    DayOfWeekFriday = 5,
    DayOfWeekSaturday = 6,
    DayOfWeekSunday = 7
};