Question

我想为我的标签使用一点动画。如果我尝试从IBAction按钮或ViewDidLoad调用此动画，并且一切正常。

- (void)animateLabelShowText:(NSString*)newText characterDelay:(NSTimeInterval)delay
{    
    [self.myLabel setText:@""];

    for (int i=0; i<newText.length; i++)
    {
        dispatch_async(dispatch_get_main_queue(),
        ^{
            [self.myLabel setText:[NSString stringWithFormat:@"%@%C", self.myLabel.text, [newText characterAtIndex:i]]];
        });

        [NSThread sleepForTimeInterval:delay];
    }
}

呼叫：

-(void) doStuff
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0),
    ^{
        [self animateLabelShowText:@"Hello Vignesh Kumar!" characterDelay:0.5];
    });
}

但是如果我把这个方法放在一个协议中，我试着从例如一个委托中调用它，什么都没有出现。可能我在GDC（Grand Central Dispatch）逻辑中遗漏了一些东西：

...
 if ([_myDelegate respondsToSelector:@selector(doStuff:)])
 {
     NSLog(@" Yes I'm in and try to execute doStuff..");
     [_myDelegate doStuff]; // NOTHING TO DO
 }
...

当我使用类似函数更改函数doStuff时发生了同样的情况：

-(void)typingLabel:(NSTimer*)theTimer
{
    NSString *theString = [theTimer.userInfo objectForKey:@"string"];
    int currentCount = [[theTimer.userInfo objectForKey:@"currentCount"] intValue];
    currentCount ++;
    NSLog(@"%@", [theString substringToIndex:currentCount]);

    [theTimer.userInfo setObject:[NSNumber numberWithInt:currentCount] forKey:@"currentCount"];

     if (currentCount > theString.length-1) {
        [theTimer invalidate];
    }

    [self.myLabel setText:[theString substringToIndex:currentCount]];
}

通过

调用

-(void) doStuff
{
    NSString *string =@"Risa Kasumi & Yuma Asami";

    NSMutableDictionary *dict = [NSMutableDictionary dictionary];
    [dict setObject:string forKey:@"string"];
    [dict setObject:@0 forKey:@"currentCount"];
    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(typingLabel:) userInfo:dict repeats:YES];
    [timer fire];
}

Answer 1

我已在我的委托文件.m

中使用NSNotificationCenter解决了问题 viewDidLoad：

中的

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(makeEffectOnMyLabel:) name:@"lblUpdate" object:nil];

我的协议功能>

dispatch_async( dispatch_get_main_queue(), ^{ ...I've populated a dictionary userInfo with my vars [[NSNotificationCenter defaultCenter] postNotificationName:@"lblUpdate" object:nil userInfo:userInfo]; });

在为准备打字标签创建的函数

-(void) makeEffectOnMyLabel:(NSNotification *) notification { ..changes between dictionaries to prepare typingLabel.. NSMutableDictionary *dict = [NSMutableDictionary dictionary]; NSDictionary* userInfo = [notification userInfo]; [dict setObject:[userInfo objectForKey:@"myRes"] forKey:@"myRes"]; [dict setObject:[userInfo objectForKey:@"myType"] forKey:@"myType"]; [dict setObject:[userInfo objectForKey:@"frase"] forKey:@"frase"]; [dict setObject:@0 forKey:@"currentCount"]; NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(typingLabel:) userInfo:dict repeats:YES]; [timer fire]; }

现在一切正常。

由委托/协议结构调用的UILabels动画

1 个答案: