iOS开发之跑马灯滚动条的两种方法与实现

跑马灯效果的滚动条，一般出现在 iOS 应用的底部。用于显示动态变化的信息或内容较长的信息，在各类应用中使用广泛。以下两种可用的跑马灯滚动 MarqueeBar 的实现。

1. 直接在 ViewController 中实现对 UIView 的位置定时移动来实现，以下代码直接加入到 ViewController 中，在 viewWillAppear 中调用 loadView 即可。

- (void)marqueeView
{
    
    CGRect frame = self.vMarqueeContainer.frame;
    frame.origin.x = frame.origin.x -2;
    if(frame.origin.x < -frame.size.width )
    {
        frame.origin.x  = 320;
    }
    self.vMarqueeContainer.frame = frame;
    
    //延时递归调用
    [self performSelector:@selector(marqueeView) withObject:nil afterDelay:0.04];
}

- (void)loadView
{
	//marqueenbar背景，位置高度等控制
    UIView *viewMarqueeBar = [[[UIView alloc]initWithFrame:CGRectMake(0, 347, 320, 20)]autorelease];
    [viewMarqueeBar setBackgroundColor:[UIColor darkGrayColor]];
    
    //滚动容器，显示滚动范围
    UIView *viewMarqueeContainer = [[[UIView alloc]initWithFrame:CGRectMake(320, 3, 360, 14)]autorelease];
    [viewMarqueeContainer setBackgroundColor:[UIColor clearColor]];
    [viewMarqueeContainer setClipsToBounds:YES];
    [viewMarqueeContainer setOpaque:YES];
    
    //内容
    UILabel *lblContent = [[[UILabel alloc]initWithFrame:CGRectMake(0, 0, 50,14)]autorelease];
    [lblContent setText:@"这里是滚动条。。。。。"];
    [lblContent setTextColor:[UIColor whiteColor]];
    [lblContent setBackgroundColor:[UIColor clearColor]];
    [lblContent setFont:[UIFont fontWithName:@"Helvetica" size:12]];
    [lblContent setOpaque:YES];
    
    self.view= viewMarqueeBar;
    self.vMarqueeContainer = viewMarqueeContainer;
    
    [self.view addSubview:viewMarqueeContainer];

    [self marqueeView];
}

2. 自行定义滚动条控件，让 view 自己滚动起来，通过不断的相互方法调用实现循环滚动 UIMarqueeBarView.h 定义

/**
 *UIMarqueeBarView.h
 */
@interface UIMarqueeBarView : UIView
{
}

- (void)start;
- (void)stop;
@end

UIMarqueeBarView.m 实现

/**
 *UIMarqueeBarView.m
 */
 
#import "UIMarqueeBarView.h"

@implementation UIMarqueeBarView

- (void)dealloc
{
    [super dealloc];
}

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
		[self setupView];
    }
    return self;
}

-(id)initWithCoder:(NSCoder *)aDecoder {
	if( (self = [super initWithCoder:aDecoder]) ) {
		// Initialization code
		[self setupView];
	}
	return self;
}

- (void)setupView
{
    [self setBackgroundColor:[UIColor lightGrayColor]];
    [self setClipsToBounds:YES];
    [self setOpaque:YES];
    
    UILabel *lblContent = [[[UILabel alloc]initWithFrame:CGRectMake(0, 0, 150 ,16)]autorelease];
    [lblContent setText:@"这里是滚动条。。。。。"];
    [lblContent setTextColor:[UIColor whiteColor]];
    [lblContent setBackgroundColor:[UIColor clearColor]];
    [lblContent setFont:[UIFont fontWithName:@"Helvetica" size:14]];
    [lblContent setNumberOfLines:1];
    [lblContent setOpaque:YES];
    
    [self addSubview:lblContent];
}

- (void)start
{
    if (self.viewContainer == NULL) {
        [self setupView];
    }

    [self startAnimation];
}
- (void)stop
{
    
}

-(void)startAnimation
{
    [UIView beginAnimations:@"MarqueeBarAniamation" context:nil];
    [UIView setAnimationCurve:UIViewAnimationCurveLinear];
    [UIView setAnimationDuration:25];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];

    CGRect viewFrame = self.viewContainer.frame;
    viewFrame.origin.x = -320;
    [self.viewContainer setFrame:viewFrame];

    [UIView commitAnimations];
}

-(void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context
{	
    CGRect viewFrame = self.viewContainer.frame;
    viewFrame.origin.x = 320;
    [self.viewContainer setFrame:viewFrame];
	[self startAnimation];
}