如果语句不是运行 - iOS

Question

我有一个 iOS 应用程序，其中包含一些简单且合乎逻辑的 if-statements。但是他们不会运行我不明白为什么。这是我的简单代码：

-(void)viewDidLoad {

    [super viewDidLoad];

    // Run setup code.

    int day = [self currentDay];

    if ((day == (1 || 3 || 7) && (day != (2 || 4 || 5 || 6))) {

        // Run the calendar setup code for
        // Sunday/Tuesday OR saturday.
        [self runSetupVX_4];
    }

    else if ((day == (2 || 4 || 5 || 6)) && (day != (1 || 3 || 7))) {

        // Run setup code for Monday
        // wednesday, thursday and friday.
        [self runSetupVX_2];
    }
}

-(int)currentDay {

    NSDateComponents *component = [[NSCalendar currentCalendar] components:NSCalendarUnitWeekday fromDate:[NSDate date]];
    return [component weekday];
}

我做错了什么？

Answer 1

你可以把断点放在if语句上，然后检查是否调用了if语句。

Answer 2

你有点过于复杂了。

 if(day==1 || day==2 || day==3){
     [self runSetupVX_4];  
 }else{
     [self runSetupVX_2];
 }

应该可以解决问题

Answer 3

这可以编译，但它做的事情与您想要实现的完全不同：

day == (1 || 3 || 7) && (day != (2 || 4 || 5 || 6)

语句 OR 1、3 和 7，然后是 OR 2、4、5 和 6，然后再执行比较。

正确的做法是将day分别与1、3、7进行比较。如果任何比较成功，也可以保证日期不是 2、4、5 或 6：

if (day == 1 || day == 3 || day == 7)
    ...
if (day == 2 || day == 4 || day == 5 || day == 6)
    ...

你也可以用switch重写这个：

switch(day) {
    case 1:
    case 3:
    case 7:
        // Run the calendar setup code for
        // Sunday/Tuesday OR saturday.
        [self runSetupVX_4];
        break;
    case 2:
    case 4:
    case 5:
    case 6:
        // Run setup code for Monday
        // wednesday, thursday and friday.
        [self runSetupVX_2];
        break;
}

Answer 4

如果每个 if 语句的第一部分为真，那么第二部分每次都为假。所以你不必检查第二部分。

您可以这样修改您的代码：

-(void)viewDidLoad {

[super viewDidLoad];

// Run setup code.

int day = [self currentDay];

if (day ==1 || day==3 || day==7) {

    // Run the calendar setup code for
    // Sunday/Tuesday OR saturday.
    [self runSetupVX_4];

}
else{

        // Run setup code for Monday
        // wednesday, thursday and friday.
        [self runSetupVX_2];


}}

-(int)currentDay {

    NSDateComponents *component = [[NSCalendar currentCalendar]          components:NSCalendarUnitWeekday fromDate:[NSDate date]];
    return [component weekday];
}

Answer 5

希望这对你有用：

if (day == 1 || day == 2 || day == 3) {

    // Run the calendar setup code for
    // Sunday/Tuesday OR Saturday.
    [self runSetupVX_4];
}

else if (day == 2 || day == 4 || day == 5 || day == 6) {

    // Run setup code for Monday
    // Wednesday, Thursday and Friday.
    [self runSetupVX_2];
}

Answer 6

-(void)viewDidLoad {

  [super viewDidLoad];

  // Run setup code.

  int day = [self currentDay];
  //if ((day == (1 || 3 || 7) && (day != (2 || 4 || 5 || 6))) {   
  //here u will get 0 or 1 from this  (1 || 3 || 7) && (day != (2 || 4 || 5 || 6))) 
  //And u r comparing with 0 or 1 with day  so please check below code how to compare 

  if (((day == 1 || 3 || 7) && (day != 2 || 4 || 5 || 6)) {

    // Run the calendar setup code for
    // Sunday/Tuesday OR saturday.
    [self runSetupVX_4];
  }

  else if ((day == 2 || 4 || 5 || 6)&& (day != 1 || 3 || 7)) {

    // Run setup code for Monday
    // wednesday, thursday and friday.
    [self runSetupVX_2];
  }
}

-(int)currentDay {

   NSDateComponents *component = [[NSCalendar currentCalendar] components:NSCalendarUnitWeekday fromDate:[NSDate date]];
   return [component weekday];
} //you have problems with comparing variable please check it

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