IOS開發-利用繪圖表示進度

(1)創建自定義view。
(2)導入QuartzCore框架
(3)在h文件，定義一個屬性，用於接收進度值，最大值是1，最小值是0:

#import <UIKit/UIKit.h>

@interface ZCView : UIView
@property(nonatomic,assign)CGFloat progress;
@end

(4)m文件的代碼如下:

#import "ZCView.h"
#import <QuartzCore/QuartzCore.h>

@interface ZCView ()
@property(nonatomic,weak)UILabel *progressLabel;
@end

@implementation ZCView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if(self)
    {
        CGFloat proX = 0;
        CGFloat proW = frame.size.width;
        CGFloat proH = 20;
        CGFloat proY = (frame.size.height-proH)/2;
        UILabel *progressLabel = [[UILabel alloc]initWithFrame:CGRectMake(proX, proY, proW, proH)];
        [progressLabel setTextAlignment:NSTextAlignmentCenter];
        self.progressLabel = progressLabel;
        [self addSubview:progressLabel];
    }
    return self;
}

- (void)drawRect:(CGRect)rect {
    //線寬
    CGFloat lineWidth = 5;
    //半徑
    CGFloat radius = (rect.size.width-lineWidth*4)/2;
    //圓心
    CGPoint center = CGPointMake(rect.size.width/2, rect.size.width/2);
    //結束弧度
    CGFloat endAngle = -M_PI_2+(_progress*M_PI*2);
    //路徑
    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:-M_PI_2 endAngle:endAngle clockwise:YES];
    [path setLineWidth:lineWidth];
    [path stroke];
}


- (void)setProgress:(CGFloat)progress
{
    _progress = progress;

    [self.progressLabel setText:[NSString stringWithFormat:@"%.2f%%",progress*100]];

    [self setNeedsDisplay];
}
@end

傳入progress的值就能刷新進度了: