前言
开发时有一个需求是实现跑马灯效果，其实跑马灯还是比较容易实现的，但是这个是一个局部范围的跑马灯，平时使用的都是全屏幕长度的跑马灯，经过一番折腾，找的了重点,下面这句代码就是我们实现局部的关键。
@property(nonatomic) BOOL clipsToBounds; // When YES, content and subviews are clipped to the bounds of the view. Default is NO.
效果图
未命名.gif
代码
//.h
#import <UIKit/UIKit.h>
@interface HHRunLabelView : UIView
//字体颜色
@property (nonatomic, strong) UIColor *textColor;
//字体大小
@property (nonatomic, strong) UIFont *font;
//要显示的内容
@property (nonatomic, strong) NSString *text;
/**
移动的速度[0~1],默认是0.2
*/
@property (nonatomic, assign) CGFloat speed;
@end
//.m
#import "HHRunLabelView.h"
@interface HHRunLabelView()
@property (nonatomic, assign) CGFloat offsetX; //x偏移量
@property (nonatomic, strong) UILabel *moveLabel;
@property (nonatomic, assign) CGFloat labelWidth; //label的宽度
@end
@implementation HHRunLabelView
- (instancetype)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]){
_speed = 0.2;//默认值
[self initView];
[self initTimer];
}
return self;
}
- (void)initView{
_moveLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
[self addSubview:_moveLabel];
}
//初始化timer
- (void)initTimer{
CADisplayLink *timer = [CADisplayLink displayLinkWithTarget:self selector:@selector(displayLabelAction)];
timer.frameInterval = 2.0;
[timer addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
}
- (void)setTextColor:(UIColor *)textColor{
_moveLabel.textColor = textColor;
}
- (void)setFont:(UIFont *)font{
_moveLabel.font = font;
}
//设置速度
- (void)setSpeed:(CGFloat)speed{
if (speed < 0) {
speed = 0;
}else if (speed > 1){
speed = 1;
}
_speed = speed*5;
}
//赋值text
- (void)setText:(NSString *)text{
_moveLabel.text = text;
[_moveLabel sizeToFit];
CGRect rect = _moveLabel.frame;
rect.size.height = self.frame.size.height;
_moveLabel.frame = rect;
_offsetX = _moveLabel.frame.origin.x;
self.clipsToBounds = YES;//设置了这个属性后才能局部显示
}
- (void)displayLabelAction{
_labelWidth = self.moveLabel.frame.size.width;
if (_labelWidth < self.frame.size.width) return;//如果字能显示全则不移动
CGRect rect = self.moveLabel.frame;
_offsetX -= self.speed;
rect.origin.x = _offsetX;
self.moveLabel.frame = rect;
if (_offsetX < -_labelWidth){
_offsetX = self.frame.size.width; //重置起点
}
}
用法
//导入头文件后加载
HHRunLabelView *runLabel = [[HHRunLabelView alloc] initWithFrame:CGRectMake(10, 100, 100, 50)];
runLabel.backgroundColor = [UIColor grayColor];
runLabel.textColor = [UIColor redColor];
runLabel.speed = 0.5;
runLabel.text = @"我是一个局部的小跑马灯啊";
[self.view addSubview:runLabel];
Demo地址github
