如果语句没有运行 - iOS

Question

我有一个iOS简单而合乎逻辑的应用程序if-statements.然而,他们不会运行,我不能理解为什么.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];
}

我在这做错了什么？

Answer 1

这会编译,但它会与您尝试实现的完全不同:

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

在执行比较之前,语句OR为1,3和7,然后是OR 2,4,5和6.

正确的方法是分别比较day1,3和7.如果任何比较成功,也保证当天不是2,4,5或6:

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

你也可以用以下内容重写switch:

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;
}