MBProgressHUD源码学习 - CrusherWu/study GitHub Wiki
1.MBProgressHUD
MBProgressHUD 是 UIView 子类，为 APP 提供透明的浮层提示。MBProgressHUD 提供的外部办法和属性：
上图为MBProgressHUD.h文件各属性，办法和类别。
2.如何使用
MBProgressHUD *hud = [MBProgressHUD showHUDAddedTo:self.tableView animated:YES];//默认动画
通过该行代码，我们来追看 MBProgressHUD 是如何加载在 view 上的。
+ (instancetype)showHUDAddedTo:(UIView *)view animated:(BOOL)animated {
MBProgressHUD *hud = [[self alloc] initWithView:view];
hud.removeFromSuperViewOnHide = YES;
[view addSubview:hud];
[hud showAnimated:animated];
return hud;
}
3.创建到显示到隐藏过程
MBProgressHUD *hud = [[self alloc] initWithView:view];
3.1总体流程
3.1.1 调用 self 的 initWithView 办法
- (id)initWithView:(UIView *)view {
NSAssert(view, @"View must not be nil.");
return [self initWithFrame:view.bounds];
}
- (instancetype)initWithFrame:(CGRect)frame {
if ((self = [super initWithFrame:frame])) {
[self commonInit];
}
return self;
}
- (void)commonInit {//初始化控件
// Set default values for properties
// Default color, depending on the current iOS version
// Transparent background
// Make it invisible for now
self.alpha = 0.0f; //初始化的时候设置不可见
[self setupViews];
[self updateIndicators];
[self registerForNotifications];//处理屏幕横竖屏切换
}
3.1.2显示
#pragma mark - Show & hide
- (void)showAnimated:(BOOL)animated {
MBMainThreadAssert();//判断是不是主线程
[self.minShowTimer invalidate];
self.useAnimation = animated;
self.finished = NO;
// If the grace time is set, postpone the HUD display
if (self.graceTime > 0.0) {
NSTimer *timer = [NSTimer timerWithTimeInterval:self.graceTime target:self selector:@selector(handleGraceTimer:) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
self.graceTimer = timer;
}
// ... otherwise show the HUD immediately
else {
[self showUsingAnimation:self.useAnimation];
}
}
#pragma mark - Internal show & hide operations
- (void)showUsingAnimation:(BOOL)animated {
// Cancel any previous animations
[self.bezelView.layer removeAllAnimations];
[self.backgroundView.layer removeAllAnimations];
// Cancel any scheduled hideAnimated:afterDelay: calls
[self.hideDelayTimer invalidate];
self.showStarted = [NSDate date];//记录开始时间
self.alpha = 1.f;
// Needed in case we hide and re-show with the same NSProgress object attached.
[self setNSProgressDisplayLinkEnabled:YES];
if (animated) {
[self animateIn:YES withType:self.animationType completion:NULL];//根据动画的类型实现不同显示动画
} else {
self.bezelView.alpha = 1.f;
self.backgroundView.alpha = 1.f;
}
}
有graceTime 的情况
- (void)handleGraceTimer:(NSTimer *)theTimer {
// Show the HUD only if the task is still running
if (!self.hasFinished) {
[self showUsingAnimation:self.useAnimation];
}
}
3.1.3 hide隐藏
- (void)hideAnimated:(BOOL)animated {
MBMainThreadAssert();
[self.graceTimer invalidate];
self.useAnimation = animated;
self.finished = YES;
// If the minShow time is set, calculate how long the HUD was shown,
// and postpone the hiding operation if necessary
if (self.minShowTime > 0.0 && self.showStarted) {
NSTimeInterval interv = [[NSDate date] timeIntervalSinceDate:self.showStarted];
if (interv < self.minShowTime) {
NSTimer *timer = [NSTimer timerWithTimeInterval:(self.minShowTime - interv) target:self selector:@selector(handleMinShowTimer:) userInfo:nil repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
self.minShowTimer = timer;
return;
}
}
// ... otherwise hide the HUD immediately
[self hideUsingAnimation:self.useAnimation];
}
有 MinShowTime 情况
- (void)handleMinShowTimer:(NSTimer *)theTimer {
[self hideUsingAnimation:self.useAnimation];
}
- (void)hideUsingAnimation:(BOOL)animated {
// Cancel any scheduled hideAnimated:afterDelay: calls.
// This needs to happen here instead of in done,
// to avoid races if another hideAnimated:afterDelay:
// call comes in while the HUD is animating out.
[self.hideDelayTimer invalidate];
if (animated && self.showStarted) {
self.showStarted = nil;
[self animateIn:NO withType:self.animationType completion:^(BOOL finished) {
[self done];
}];
} else {
self.showStarted = nil;
self.bezelView.alpha = 0.f;
self.backgroundView.alpha = 1.f;
[self done];
}
}
隐藏后需要完成的事务--done
- (void)done {
[self setNSProgressDisplayLinkEnabled:NO];
if (self.hasFinished) {
self.alpha = 0.0f;
if (self.removeFromSuperViewOnHide) {
[self removeFromSuperview];
}
}
MBProgressHUDCompletionBlock completionBlock = self.completionBlock;
if (completionBlock) {
completionBlock();
}
id<MBProgressHUDDelegate> delegate = self.delegate;
if ([delegate respondsToSelector:@selector(hudWasHidden:)]) {
[delegate performSelector:@selector(hudWasHidden:) withObject:self];
}
}
3.1.4 延迟隐藏 -- hide after delay
- (void)hideAnimated:(BOOL)animated afterDelay:(NSTimeInterval)delay {
// Cancel any scheduled hideAnimated:afterDelay: calls
[self.hideDelayTimer invalidate];
NSTimer *timer = [NSTimer timerWithTimeInterval:delay target:self selector:@selector(handleHideTimer:) userInfo:@(animated) repeats:NO];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
self.hideDelayTimer = timer;
}
- (void)handleHideTimer:(NSTimer *)timer {
[self hideAnimated:[timer.userInfo boolValue]];
}
补充：
- (void)setNSProgressDisplayLinkEnabled:(BOOL)enabled {
// We're using CADisplayLink, because NSProgress can change very quickly and observing it may starve the main thread,
// so we're refreshing the progress only every frame draw
if (enabled && self.progressObject) {
// Only create if not already active.
if (!self.progressObjectDisplayLink) {
self.progressObjectDisplayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(updateProgressFromProgressObject)];
}
} else {
self.progressObjectDisplayLink = nil;
}
}
使用 NSProgress 的情况，如果使用 KVO 来监听 NSProgress 的变化来更新UI ，会很消耗主线程，所以使用 CADisplayLink 来刷新 UI。CADisplayLink是一个能让我们以和屏幕刷新率同步的频率将特定的内容画到屏幕上的定时器类。CADisplayLink有一个整型属性frameInterval,每隔多少帧调用一次。默认值是1，也就是在每次屏幕刷新之前调用一次。每秒调用次数 = 60 / frameInterval。CADisplayLink不能保证每秒调用60次，这也取决于CPU的使用情况，如果在CPU忙碌的情况下丢帧，CADisplayLink是不会再去执行已经丢的帧，而是忽略掉进行下一次的更新。
4 站在巨人的肩膀上
4.1 小细节:
当初始化控件的类别相同，和其某些属性是一样的时候，可以一起设置这些属性的参数。
for (UIView *view in @[label, detailsLabel, button]) {
view.translatesAutoresizingMaskIntoConstraints = NO;
[view setContentCompressionResistancePriority:998.f forAxis:UILayoutConstraintAxisHorizontal];
[view setContentCompressionResistancePriority:998.f forAxis:UILayoutConstraintAxisVertical];
[bezelView addSubview:view];
}
4.2 静态 UITableView
- (void)awakeFromNib {
[super awakeFromNib];
self.examples =
@[@[[MBExample exampleWithTitle:@"Indeterminate mode" selector:@selector(indeterminateExample)],
[MBExample exampleWithTitle:@"With label" selector:@selector(labelExample)],
[MBExample exampleWithTitle:@"With details label" selector:@selector(detailsLabelExample)]]
];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
MBExample *example = self.examples[indexPath.section][indexPath.row];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MBExampleCell" forIndexPath:indexPath];
cell.textLabel.text = example.title;
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
MBExample *example = self.examples[indexPath.section][indexPath.row];
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
[self performSelector:example.selector];
#pragma clang diagnostic pop
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[tableView deselectRowAtIndexPath:indexPath animated:YES];
});
}
可以通过构造数据源的方式来实现静态表格，不用在代理办法中使用 if - else if - else 的方式，一来不好维护，二来代码也不够优雅。
5总结
MBProgressHUD总体上还是比较清晰，简单的，对于初步学习源码是非常不错的选择，同时可以学习一下作者一些小技巧等等。