呈现 UIViewController 时引入的延迟

Question

我正在开发应用程序，在该应用程序中我使用 [self performSegueWithIdentifier:@"newViewSegue" sender:self]; 从另一个人那里呈现新的 UIViewController

在新的UIViewController 中，我正在初始化我的视图元素并以编程方式将UITableView 添加到其中。

但是当我调用这个performSegueWithIdentifier new UIViewController 在延迟一段时间后显示时，我尝试在viewDidLoad 的新UIViewController 和[self performSegueWithIdentifier:@"newViewSegue" sender:self]; 语句之前输入日志，这两个语句都会立即执行，但会显示视图一段时间后。

我的ViewDidLoad方法如下：

-(void)viewDidLoad{
sharedObject=[SingleToneClass sharedManager];

    selectedButtonTag=-1;

    initFlag=0;
    NSLog(@"End %@",[NSDate date]);
    backgroundView.backgroundColor=[self hexToUiColor:@"E7E7E7"];

    [mondayDateButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    //set colour for all 7days buttons

    [mondayDateButton.titleLabel setFont:[UIFont boldSystemFontOfSize:14]];
    //Set font for all days button

    [mondayButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
   //set title colour

    [mondayButton.titleLabel setFont:[UIFont systemFontOfSize:12]];
    //set font

    //Changing image Color
    //Home Button
    [homeButton.titleLabel setFont:[UIFont fontWithName:kFontAwesomeFamilyName size:40]];
    [homeButton setTitleColor:[self hexToUiColor:sharedObject.secondaryHexColorCode] forState:UIControlStateNormal];
    [homeButton setTitle:[NSString fontAwesomeIconStringForIconIdentifier:@"fa-home"] forState:UIControlStateNormal];

    //Back Button
    [backButton.titleLabel setFont:[UIFont fontWithName:kFontAwesomeFamilyName size:27]];
    [backButton setTitleColor:[self hexToUiColor:sharedObject.secondaryHexColorCode] forState:UIControlStateNormal];
    [backButton setTitle:[NSString fontAwesomeIconStringForIconIdentifier:@"fa-chevron-left"] forState:UIControlStateNormal];

    //Next Week Button
    [nextWeek.titleLabel setFont:[UIFont fontWithName:kFontAwesomeFamilyName size:20]];
    [nextWeek setTitleColor:[self hexToUiColor:sharedObject.secondaryHexColorCode] forState:UIControlStateNormal];
    [nextWeek setTitle:[NSString fontAwesomeIconStringForIconIdentifier:@"fa-chevron-right"] forState:UIControlStateNormal];

    //Previous Week Button
    [previousWeek.titleLabel setFont:[UIFont fontWithName:kFontAwesomeFamilyName size:20]];
    [previousWeek setTitleColor:[self hexToUiColor:sharedObject.secondaryHexColorCode] forState:UIControlStateNormal];
    [previousWeek setTitle:[NSString fontAwesomeIconStringForIconIdentifier:@"fa-chevron-left"] forState:UIControlStateNormal];

    [separatorLineView setBackgroundColor:[self hexToUiColor:@"6D6D6D"]];
    [selectLabel setTextColor:[self hexToUiColor:@"6D6D6D"]];


    [selectLabel setFont:[UIFont boldSystemFontOfSize:13]];
    selectLabel.text=[NSString stringWithFormat:@"%@",selectedTitle];
    sharedObject.bookADateTitle=selectedTitle;

    //make Buttons Rounded

    mondayDateButton.clipsToBounds = YES;
    mondayDateButton.layer.cornerRadius = mondayDateButton.frame.size.height/2;


    NSDate *currentDate;
    if (sharedObject.bookDateViewDate.length>0) {
        NSDateFormatter *dateFormat1 = [[NSDateFormatter alloc] init];
        [dateFormat1 setDateFormat:@"yyyy-MM-dd"];
        currentDate=[dateFormat1 dateFromString:sharedObject.bookDateViewDate];
    }
    else{
        currentDate=[NSDate date];
    }

    [self setDate:currentDate];

    [self setDateToLabel:currentDate]; //set formatted date 


//create and initialise UITableView
    static NSString *cellIdentifier=@"CustomHiddenViewCell";
    CustomHiddenViewCell *cell = (CustomHiddenViewCell *)[slotsTableView dequeueReusableCellWithIdentifier:cellIdentifier];
    NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"CustomHiddenViewCell" owner:self options:nil];
    cell = [nib objectAtIndex:0];

    double heightOfTable=(self.view.frame.size.height-backgroundView.frame.size.height);

    //creating tableview1
    slotsTableView=[[UITableView alloc]initWithFrame:CGRectMake(self.view.frame.origin.x,self.view.frame.origin.y+backgroundView.frame.size.height,self.view.frame.size.width,heightOfTable)];
    slotsTableView.scrollEnabled=YES;
    slotsTableView.delegate=self;
    [slotsTableView flashScrollIndicators];
    slotsTableView.dataSource=self;
    slotsTableView.bounces=NO;
    slotsTableView.showsVerticalScrollIndicator=YES;
    slotsTableView.separatorStyle=UITableViewCellSeparatorStyleNone;
    [self.view addSubview:slotsTableView];

    //add swipe gesture
    UISwipeGestureRecognizer *leftSwipRecognizer;
    leftSwipRecognizer = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(SwipeRecognizer:)];
    [leftSwipRecognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
    [slotsTableView addGestureRecognizer:leftSwipRecognizer];

    UISwipeGestureRecognizer *rightSwipRecognizer;
    rightSwipRecognizer = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(SwipeRecognizer:)];
    [rightSwipRecognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
    [slotsTableView addGestureRecognizer:rightSwipRecognizer];

    [leftWeekRecognizer addTarget:self action:@selector(WeekSwipeRecognizer:)];
    [leftWeekRecognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];

    [rightWeekRecognizer addTarget:self action:@selector(WeekSwipeRecognizer:)];
    [rightWeekRecognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
}

谁能告诉我为什么会引入这种延迟？

Answer 1

可能是您的代码在主线程中执行，在主线程中移动您的代码或使用 GCD 之类的

dispatch_async(dispatch_get_main_queue(), ^(void){
    //Run UI Updates
});