objective-c - 以特定间隔显示 NSArray

Question

我有一个 NSArray，我想以特定的时间间隔显示每个对象，例如:

NSArray *array = [NSArray arrayWithObjects:@"foo",@"bar",@"baz",nil];

并输出:

for (object in array) {
     NSLog(@"%@", object);
     // wait 3 seconds then show next object
}

所以它应该这样做:

foo 
... wait three seconds 
bar
... wait three seconds
baz
... wait three seconds
repeat

我该怎么做？

Answer 1

最简单的方法是使用 block ...

您可以使用第三方类别探索如何使用 block 来执行此操作，例如: https://github.com/zwaldowski/BlocksKit

至于没有 block 的解决方案:

@property (nonatomic, strong) NSArray *myArray;
@property (nonatomic) NSInteger iteration;

- (void)awakeFromNib //Or equivalent method called when you want to start scheduling..
{
    self.myArray = [NSArray arrayWithObjects:@"foo",@"bar",@"baz",nil];
    self.iteration = 0;

    [NSTimer scheduledTimerWithTimeInterval:3  
             target:self
             selector:@selector(fireEvent) 
             userInfo:nil 
             repeats:YES]; //Will Fire every 3 seconds...
}

-(void)fireEvent
{
     NSLog(@"%@", [self.myArray objectAtIndex:self.iteration]);
     self.iteration++;
     if (self.iteration>=self.myArray.count) self.iteration=0;
}

如果您要在显示数组中的所有元素后使计时器无效。执行以下操作:

-(void)awakeFromNib //Or equivalent method called when you want to start scheduling..
{
    self.myArray = [NSArray arrayWithObjects:@"foo",@"bar",@"baz",nil];
    self.iteration = 0;

    [NSTimer scheduledTimerWithTimeInterval:3
             target:self
             selector:@selector(fireEvent:)
             userInfo:nil
             repeats:YES]; //Will Fire every 3 seconds...
}

-(void)fireEvent:(NSTimer*)timer
{
    NSLog(@">>>> %@", [self.myArray objectAtIndex:self.iteration]);
    self.iteration++;
    if (self.iteration>=self.myArray.count) {
        self.iteration=0;
        [timer invalidate];
    }
}

注意:后面的代码仅向 @selector(fireEvent:) 添加一个“:”。并读取fireEvent中的NSTimer引用作为参数。