重绘-下载进度条(setNeedsDisplay)的步骤
- 布局控件：UISliderView,自定义view用来画圆弧进度条,UILabel
功能一：UILabel的text值与UISliderView相关，监听UISliderView的进度，显示text值
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功能二：圆弧进度条的长度与与UISliderView相关，监听UISliderView的进度，显示圆弧进度条
- 绘制圆弧
- 根据新进度值重新绘制圆弧
在progressView.m中
- (void)setProgress:(CGFloat)progress
{
_progress = progress;
// 每次获取新进度后重绘
[self setNeedsDisplay];
}
- (void)drawRect:(CGRect)rect {
// Drawing code
CGPoint center = CGPointMake(rect.size.width * 0.5, rect.size.height * 0.5);
//- M_PI_2表示从12点钟位置开始绘制
CGFloat endA = - M_PI_2 + M_PI * 2 * _progress;
// 圆弧
UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:rect.size.width * 0.5 - 4 startAngle:-M_PI_2 endAngle:endA clockwise:YES];
[path stroke];
}
在vc.m中
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *labelView;
@property (weak, nonatomic) IBOutlet ProgressView *progressView;
@end
@implementation ViewController
//监控进度条UISliderView
- (IBAction)valueChange:(UISlider *)sender {
// 在@“”中转义字符%% = %
_labelView.text = [NSString stringWithFormat:@"%.2f%%",sender.value * 100];
// 传入下载进度
_progressView.progress = sender.value;
}
