SVProgressHUD是iOS开发中比较常用的一个三方库，用来在执行耗时操作或者指示用户操作结果的场合，由于使用简单，功能丰富，交互友好，被广泛应用。本文从源码的角度，解读一下实现的过程，希望能起到抛砖引玉的作用。
一. 效果预览
1. SVPIndefiniteAnimatedView
2. SVProgressAnimatedView
3. SVRadialGradientLayer
二. 类分析
1. SVProgressHUD
这是SVProgressHUD显示提示框的类，提供类方法和属性来进行不同的设置。
** HUD提示框背景
typedef NS_ENUM(NSInteger, SVProgressHUDStyle) {
SVProgressHUDStyleLight, // 白色
SVProgressHUDStyleDark, // 黑色
SVProgressHUDStyleCustom // 用户自定义
};
** 遮罩层背景
typedef NS_ENUM(NSUInteger, SVProgressHUDMaskType) {
SVProgressHUDMaskTypeNone = 1, // 默认mask，用户和交互
SVProgressHUDMaskTypeClear, // 不允许交互
SVProgressHUDMaskTypeBlack, // 不允许交互，遮罩层呈黑色部分透明
SVProgressHUDMaskTypeGradient, // 不允许交互，遮罩层呈渐变效果
SVProgressHUDMaskTypeCustom // 不允许交互，遮罩层颜色自定义
};
** 无限循环的显示类型
typedef NS_ENUM(NSUInteger, SVProgressHUDAnimationType) {
SVProgressHUDAnimationTypeFlat, // SVPIndefiniteAnimatedView
SVProgressHUDAnimationTypeNative // 系统的UIActivityIndicatorView
};
**常用属性介绍
hud最小尺寸，默认是（100，100）
@property (assign, nonatomic) CGSize minimumSize UI_APPEARANCE_SELECTOR;
圆环厚度，默认是2px
@property (assign, nonatomic) CGFloat ringThickness UI_APPEARANCE_SELECTOR;
圆环半径，默认是18px
@property (assign, nonatomic) CGFloat ringRadius UI_APPEARANCE_SELECTOR;
提示语字体，默认是14px
@property (strong, nonatomic) UIFont *font UI_APPEARANCE_SELECTOR;
Image提示框显示时间，默认是5s
@property (assign, nonatomic) NSTimeInterval minimumDismissTimeInterval;
** 常用方法介绍
- 无限循环状态显示，不会自动小时，需主动调用
dismiss方法
+ (void)show;
+ (void)showWithStatus:(NSString*)status;
+ (void)dismiss;
+ (void)dismissWithCompletion:(SVProgressHUDDismissCompletion)completion;
+ (void)dismissWithDelay:(NSTimeInterval)delay;
+ (void)dismissWithDelay:(NSTimeInterval)delay completion:(SVProgressHUDDismissCompletion)completion;
- 进度条状态显示
+ (void)showProgress:(float)progress;
+ (void)showProgress:(float)progress status:(NSString*)status;
- 图片状态显示
+ (void)showInfoWithStatus:(NSString*)status;
+ (void)showSuccessWithStatus:(NSString*)status;
+ (void)showErrorWithStatus:(NSString*)status;
hud距离中心点的偏移量
+ (void)setOffsetFromCenter:(UIOffset)offset;
+ (void)resetOffsetFromCenter;
** 通知
通过监听不同的通知事件，可以获取hud的状态
extern NSString * const SVProgressHUDWillDisappearNotification;
extern NSString * const SVProgressHUDDidDisappearNotification;
extern NSString * const SVProgressHUDWillAppearNotification;
extern NSString * const SVProgressHUDDidAppearNotification;
** hud显示流程
SVProgressHUD采用单例模式，简化代码维护；同时，根据SVProgressHUD的层级结构可以看出，从底层到顶层依次是：UIControl (overlayView) -> SVProgressHUD -> UIView (hudView) -> UIVisualEffectView -> AnimatedView (具体动画视图) 。
-(void)showStatus:(NSString*)status, 这是显示无限循环状态的提示框，可以添加文字进一步详细补充。其中，SVProgressHUD采用图形和文字分离的模式，方面文字视图的复用。所有，显示文字的视图，最终都会调用下面的方法。
- (void)showStatus:(NSString*)status {
// 更新frame及位置，因为frame是更加status来确定的而postion是根据参数控制的。
[self updateHUDFrame];
[self positionHUD:nil];
// 更新 accesibilty 和是否可以点击
if(self.defaultMaskType != SVProgressHUDMaskTypeNone) {
self.accessibilityLabel = status;
self.isAccessibilityElement = YES;
} else {
self.hudView.accessibilityLabel = status;
self.hudView.isAccessibilityElement = YES;
}
// Show if not already visible
// Checking one alpha value is sufficient as they are all the same
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000
if(self.hudView.contentView.alpha != 1.0f){
#else
根据alpha值判断是是否可见
if(self.hudView.alpha != 1.0f){
#endif
// 如果之前不可见则发出SVProgressHUDWillAppearNotification通知，告诉马上显示
[[NSNotificationCenter defaultCenter] postNotificationName:SVProgressHUDWillAppearNotification
object:self
userInfo:[self notificationUserInfo]];
//缩放效果
self.hudView.transform = CGAffineTransformScale(self.hudView.transform, 1.3, 1.3);
// Activate blur on view before animation on older iOS versions,
// as we cannot animate this property and use alpha values instead
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000
bool greateriOS9 = kCFCoreFoundationVersionNumber >= kCFCoreFoundationVersionNumber_iOS_9_0;
if (self.defaultStyle != SVProgressHUDStyleCustom && !greateriOS9) {
[self addBlur];
// Update alpha
self.hudView.contentView.alpha = 1.0f;
}
#endif
// Define blocks
__block void (^animationsBlock)(void) = ^{
// Shrink HUD to finish pop up animation
self.hudView.transform = CGAffineTransformScale(self.hudView.transform, 1/1.3f, 1/1.3f);
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000
if(self.defaultStyle != SVProgressHUDStyleCustom && greateriOS9){
// Fade in blur effect
[self addBlur];
// Update alpha
self.hudView.contentView.alpha = 1.0f;
} else {
// This gives a warning on iOS 8, however it works, see #703
self.hudView.alpha = 1.0f;
}
#else
self.hudView.alpha = 1.0f;
self.hudView.contentView.alpha = 1.0f;
#endif
self.backgroundView.alpha = 1.0f;
};
__block void (^completionBlock)(void) = ^{
// Check if we really achieved to show the HUD (<=> alpha values are applied)
// and the change of these values has not been cancelled in between e.g. due to a dismissal
// Checking one alpha value is sufficient as they are all the same
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000
if(self.hudView.contentView.alpha == 1.0f){
#else
if(self.hudView.alpha == 1.0f){
#endif
// Register observer <=> we now have to handle orientation changes etc.
[self registerNotifications];
// Post notification to inform user
[[NSNotificationCenter defaultCenter] postNotificationName:SVProgressHUDDidAppearNotification
object:self
userInfo:[self notificationUserInfo]];
}
// 更新 accesibilty
UIAccessibilityPostNotification(UIAccessibilityScreenChangedNotification, nil);
UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification, status);
};
if (self.fadeInAnimationDuration > 0) {
// 如果设置了动画时间则进行动画效果
[UIView animateWithDuration:self.fadeInAnimationDuration
delay:0
options:(UIViewAnimationOptions) (UIViewAnimationOptionAllowUserInteraction | UIViewAnimationCurveEaseIn | UIViewAnimationOptionBeginFromCurrentState)
animations:^{
animationsBlock();
} completion:^(BOOL finished) {
completionBlock();
}];
} else {
animationsBlock();
completionBlock();
}
// 完成了更新视图层次，视图的frame以及视图的各种属性之后，告诉系统稍微进行重绘
[self setNeedsDisplay];
}
}
-(void)showProgress:(float)progress status:(NSString*)status，这是显示单次滚动效果的提示框，每次显示视图前，都会取消其它视图，防止上次显示不同视图产生的干扰。其中，在设置strokeEnd时，使用事物类CATransaction，确保操作不被干扰。
- (void)showProgress:(float)progress status:(NSString*)status {
__weak SVProgressHUD *weakSelf = self;
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
__strong SVProgressHUD *strongSelf = weakSelf;
if(strongSelf){
// 更新并且检查视图层次确保SVProgressHUD可见
[strongSelf updateViewHierarchy];
// 重置imageView和消失时间。防止之前调用过，使用上次存在的样式设置
strongSelf.imageView.hidden = YES;
strongSelf.imageView.image = nil;
if(strongSelf.fadeOutTimer) {
strongSelf.activityCount = 0;
}
strongSelf.fadeOutTimer = nil;
// 更新statusLabel显示的内容和显示的进度
strongSelf.statusLabel.text = status;
strongSelf.progress = progress;
//根据progersss的值来确定正确的样式，当progress>=0的时候，显示进度样式，当progress = -1的时候为无限旋转的样式
if(progress >= 0) {
// 防止上次为无限旋转的样式导致重叠
[strongSelf cancelIndefiniteAnimatedViewAnimation];
// 添加进度视图到hudview上，并且设置当前进度值
if(!strongSelf.ringView.superview){
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000
[strongSelf.hudVibrancyView.contentView addSubview:strongSelf.ringView];
#else
[strongSelf.hudView addSubview:strongSelf.ringView];
#endif
}
if(!strongSelf.backgroundRingView.superview){
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000
[strongSelf.hudVibrancyView.contentView addSubview:strongSelf.backgroundRingView];
#else
[strongSelf.hudView addSubview:strongSelf.backgroundRingView];
#endif
}
// Set progress animated
[CATransaction begin];
[CATransaction setDisableActions:YES];
strongSelf.ringView.strokeEnd = progress;
[CATransaction commit];
// 更新activityCount
if(progress == 0) {
strongSelf.activityCount++;
}
} else {
// 防止上次为进度的样式导致重叠
[strongSelf cancelRingLayerAnimation];
// 增加无限旋转视图到hudview上
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000
[strongSelf.hudVibrancyView.contentView addSubview:strongSelf.indefiniteAnimatedView];
#else
[strongSelf.hudView addSubview:strongSelf.indefiniteAnimatedView];
#endif
if([strongSelf.indefiniteAnimatedView respondsToSelector:@selector(startAnimating)]) {
[(id)strongSelf.indefiniteAnimatedView startAnimating];
}
// Update the activity count
strongSelf.activityCount++;
}
// 显示提示的文字信息
[strongSelf showStatus:status];
// Tell the Haptics Generator to prepare for feedback, which may come soon
#if TARGET_OS_IOS && __IPHONE_OS_VERSION_MAX_ALLOWED >= 100000
[strongSelf.hapticGenerator prepare];
#endif
}
}];
}
-(void)showImage:(UIImage*)image status:(NSString*)status duration:(NSTimeInterval)duration，这是显示带Image的提示框，自带info/success/error三种类型，也可以自定义图片。
- (void)showImage:(UIImage*)image status:(NSString*)status duration:(NSTimeInterval)duration {
__weak SVProgressHUD *weakSelf = self;
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
__strong SVProgressHUD *strongSelf = weakSelf;
if(strongSelf){
// 更新并且检查视图层次确保SVProgressHUD可见
[strongSelf updateViewHierarchy];
// 重置progress，并取消其它动画
strongSelf.progress = SVProgressHUDUndefinedProgress;
[strongSelf cancelRingLayerAnimation];
[strongSelf cancelIndefiniteAnimatedViewAnimation];
// 更新imageView
UIColor *tintColor = strongSelf.foregroundColorForStyle;
UIImage *tintedImage = image;
if (image.renderingMode != UIImageRenderingModeAlwaysTemplate) {
tintedImage = [image imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
}
strongSelf.imageView.tintColor = tintColor;
strongSelf.imageView.image = tintedImage;
strongSelf.imageView.hidden = NO;
// 更新文字
strongSelf.statusLabel.text = status;
// 显示文字视图
[strongSelf showStatus:status];
// An image will be dismissed automatically. Therefore, we start a timer
// which then will call dismiss after the predefined duration
// 添加定时消失timer
strongSelf.fadeOutTimer = [NSTimer timerWithTimeInterval:duration target:strongSelf selector:@selector(dismiss) userInfo:nil repeats:NO];
[[NSRunLoop mainRunLoop] addTimer:strongSelf.fadeOutTimer forMode:NSRunLoopCommonModes];
}
}];
}
**其它方法
- 设置
hud位置的方法
- (void)positionHUD:(NSNotification*)notification
- 调整
hud尺寸的方法
- (void)updateHUDFrame
- 更新模糊背景视图的方法
- (void)updateBlurBounds
2. SVPIndefiniteAnimatedView 类
这个类提供了一个无线旋转的动画，实现方法是把一个颜色渐变的图片旋转，然后利用UIBezierPath/CAShapeLayer/Mask等遮住不需要的部分，最后利用CABasicAnimation设置无限旋转动画。其中，核心部分是利用layer的mask属性实现遮罩功能，而mask的实现方法是显示显示bounds的非透明部分，实例图如下：
3. SVProgressAnimatedView 类
这个类提供一个画圆环的视图，通过不断改变layer的strokeEnd的值，实现了进度的显示。顺便提一下，storkeStart使用的默认值是0, 所以是从正上方开始的。
- (void)setStrokeEnd:(CGFloat)strokeEnd {
_strokeEnd = strokeEnd;
_ringAnimatedLayer.strokeEnd = _strokeEnd;
}
4. SVRadialGradientLayer 类
这个类继承自CALayer，通过CGContextDrawRadialGradient来画渐变颜色层；其中，CoreFoundation中通过create创建的需要用release释放，否则会造成内存泄漏。
至此，SVProgressHUD分析暂告一段落，分析的不全面的地方，欢迎交流。