我们经常可以在荧屏上看到滚动的字体(可以叫跑马灯)感觉挺炫的, 今天分享一下他的代码实现, 这个一般在手机上的navigationitem的title上用到. 其实就是一个自定义的View.
首先看一下效果,
111.gif
custom.h
#import <UIKit/UIKit.h>
@interface CustomView : UIView
/** 类方法 */
// 参数1: 自定义View的frame
// 参数2: 要显示的字符串
// 参数3: 自定义View的背景色
// 参数4: 字符串的颜色
// 参数5: 字符串的大小
+ (CustomView *)shareInitWithFrame:(CGRect)frame title:(NSString *)title backColor:(UIColor *)backColor textColor:(UIColor *)textColor textFont:(CGFloat)textFont;
/** init */
- (instancetype)initWithFrame:(CGRect)frame title:(NSString *)title backColor:(UIColor *)backColor textColor:(UIColor *)textColor textFont:(CGFloat)textFont;
/** 开始 */
- (void)start:(UIColor *)color;
/** 停止 */
- (void)stop;
@end
custom.m
#import "CustomView.h"
@implementation CustomView
{
CGRect rectMark1; // 标记开始位置
CGRect rectMark2; // 标记结束位置
NSMutableArray *labelArr; // label数组
NSTimeInterval timeInterval; // 时间
BOOL isStop; // 是否停止
}
+ (CustomView *)shareInitWithFrame:(CGRect)frame title:(NSString *)title backColor:(UIColor *)backColor textColor:(UIColor *)textColor textFont:(CGFloat)textFont {
static CustomView *customView = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
customView = [[CustomView alloc] initWithFrame:frame title:title backColor:backColor textColor:textColor textFont:textFont];
});
return customView;
}
- (instancetype)initWithFrame:(CGRect)frame title:(NSString *)title backColor:(UIColor *)backColor textColor:(UIColor *)textColor textFont:(CGFloat)textFont {
self = [super initWithFrame:frame];
if (self) {
// 中间间隔
title = [NSString stringWithFormat:@" %@ ", title];
timeInterval = [self displayDurationForString:title];
self.backgroundColor = backColor;
self.clipsToBounds = YES;
UILabel *textLabel = [[UILabel alloc] initWithFrame:CGRectZero];
textLabel.textColor = [UIColor clearColor];
textLabel.font = [UIFont boldSystemFontOfSize:textFont];
textLabel.text = title;
// 计算textLabel大小
CGSize sizeOftext = [textLabel sizeThatFits:CGSizeZero];
rectMark1 = CGRectMake(0, 0, sizeOftext.width, self.bounds.size.height);
rectMark2 = CGRectMake(rectMark1.origin.x + rectMark1.size.width, 0, sizeOftext.width, self.bounds.size.height);
textLabel.frame = rectMark1;
[self addSubview:textLabel];
labelArr = [NSMutableArray arrayWithObject:textLabel];
// 判断是否需要reserveTextLabel
BOOL useReserve = sizeOftext.width > frame.size.width ? YES : NO;
if (useReserve) {
UILabel *reserveTextLabel = [[UILabel alloc] initWithFrame:rectMark2];
reserveTextLabel.textColor = textColor;
reserveTextLabel.font = [UIFont boldSystemFontOfSize:textFont];
reserveTextLabel.text = title;
[self addSubview:reserveTextLabel];
[labelArr addObject:reserveTextLabel];
[self customAnimate:textColor];
}
}
return self;
}
- (void)customAnimate:(UIColor *)color {
if (!isStop) {
UILabel *labelIndex0 = labelArr[0];
UILabel *labelIndex1 = labelArr[1];
[UIView transitionWithView:self duration:timeInterval options:UIViewAnimationOptionCurveLinear animations:^{
labelIndex0.frame = CGRectMake(-rectMark1.size.width, 0, rectMark1.size.width, rectMark1.size.height);
labelIndex0.textColor = color;
labelIndex1.frame = CGRectMake(labelIndex0.frame.origin.x + labelIndex0.frame.size.width, 0, labelIndex1.frame.size.width, labelIndex1.frame.size.height);
} completion:^(BOOL finished) {
labelIndex0.frame = rectMark2;
labelIndex1.frame = rectMark1;
[labelArr replaceObjectAtIndex:0 withObject:labelIndex1];
[labelArr replaceObjectAtIndex:1 withObject:labelIndex0];
[self customAnimate:color];
}];
}
}
- (void)start:(UIColor *)color {
isStop = NO;
UILabel *labelIndex0 = labelArr[0];
UILabel *labelIndex1 = labelArr[1];
labelIndex0.frame = rectMark2;
labelIndex1.frame = rectMark1;
[labelArr replaceObjectAtIndex:0 withObject:labelIndex1];
[labelArr replaceObjectAtIndex:1 withObject:labelIndex0];
[self customAnimate:color];
}
- (void)stop {
isStop = NO;
}
// 计算一下时间间隔
- (NSTimeInterval)displayDurationForString:(NSString *)string {
return string.length / 4;
}
@end
然后在VC中创建使用类方法调用就可以了
VC.m
#import "ViewController.h"
#import "CustomView.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.navigationController.navigationBar.backgroundColor = [UIColor whiteColor];
NSString *str = @"里约奥运会上, 中国篮球队VS美国队 中国队员虽不敌美国队, 但是学到和强队带球, 学到了不少经验";
CustomView *customView = [CustomView shareInitWithFrame:CGRectMake(0, 0, 200, 40) title:str backColor:[UIColor whiteColor] textColor:[UIColor blackColor] textFont:17];
self.navigationItem.titleView = customView;
}
这样一个简单的滚动字体就完事了. 感觉还可以.
