如何在目标c中使用timer调用函数时传递参数

Question

-(void)setX:(int)x andY:(int)y andObject:(Sprite*)obj
{
    [obj setPosition:CGPointMake(x,y)];
}

现在,我想使用以下计时器调用上面的方法.

[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector() userInfo:nil repeats:NO];

在这里设置什么？

如何传递参数？(根据我的知识 - 选择器仅指定要调用的方法)

Answer 1

你需要改为使用+[NSTimer scheduledTimerWithTimeInterval:invocation:repeats:].默认情况下,用于触发计时器的选择器需要一个参数.如果您需要其他内容,则必须创建一个NSInvocation对象,而计时器将使用该对象.

Answer 2

如果你想要使用一组相当复杂的参数来调用方法,我建议将参数捕获到包含配置的东西中,并且可以根据该配置做任何需要做的事情......

像这样的界面的东西:

PositionSetter.h:

@interface  PositionSetter : NSObject
{
    NSInteger x;
    NSInteger y;
    Sprite *target;
}

+ positionSetterWithX: (NSInteger) xPos y: (NSInteger) yPos sprite: (Sprite *) aSprite; 

- (void) applyPosition;
@end

PositionSetter.m:

@interface PositionSetter()
@property(readwrite, nonatomic) NSInteger x;
@property(readwrite, nonatomic) NSInteger y;
@property(readwrite, nonatomic, retain) Sprite *target;
@end

@implementation PositionSetter
@synthesize x, y, target;

+ positionSetterWithX: (NSInteger) xPos y: (NSInteger) yPos sprite: (Sprite *) aSprite; 
{
    PositionSetter *positionSetter = [PositionSetter new];
    positionSetter.x = xPos;
    positionSetter.y = yPos;
    positionSetter.target = aSprite;
    return [positionSetter autorelease];
}

- (void) applyPosition;
{
    [self.target setPosition:CGPointMake(self.x,self.y)];
}
@end

用法很简单:

positionSetter = [PositionSetter positionSetterWithX: 42 y: 21 sprite: mySprite];
[positionSetter performSelector: @selector(applyPosition) withObject: nil afterDelay: 1.0];

虽然代码更多,但最终的实现速度足够快 - 可能比NSInvocation更快,但速度足够快,因为这将导致绘图 - 并且更加灵活.我很容易看到将上述内容重构为驾驶,比如CoreAnimation.

Answer 3

复制自Matt Ball的回答:

    - (void)startMyTimer {
        /* ... Some stuff ... */
        NSDictionary *userDict;
        userDict = [NSDictionary dictionaryWithObjectsAndKeys:someValue,
                                                              @"value1",
                                                              someOtherValue,
                                                              @"value2", nil];

        [NSTimer scheduledTimerWithTimeInterval:0.1
                                         target:self
                                       selector:@selector(callMyMethod:)
                                       userInfo:userDict
                                        repeats:YES];
}
    - (void)callMyMethod:(NSTimer *)theTimer {
        NSString *value1 = [[theTimer userInfo] objectForKey:@"value1"];
        NSString *value2 = [[theTimer userInfo] objectForKey:@"value2"];
        [self myMethod:value1 setValue2:value2];
    }