MBProgressHUD源码分析
本文为系列文章读源代码学习iOS开发中的一篇，相关文章：
MBProgressHUD是一个非常常用的iOS库，用于显示提示文字。作者实现得也非常精简，只有两个文件MBProgressHUD.m和MBProgressHUD.h，再不用cocoapods的情况下，也非常容易集成到自己的项目。
兼容性处理
首先因为MBProgressHUD支持ARC和非ARC，所以用了几个宏：
# if __has_feature(objc_arc)
#define MB_AUTORELEASE(exp) exp
#define MB_RELEASE(exp) exp
#define MB_RETAIN(exp) exp
# else
#define MB_AUTORELEASE(exp) [exp autorelease]
#define MB_RELEASE(exp) [exp release]
#define MB_RETAIN(exp) [exp retain]
# endif另外，为了兼容iOS老版本的API，用到了：
# if __IPHONE_OS_VERSION_MIN_REQUIRED >= 60000
#define MBLabelAlignmentCenter NSTextAlignmentCenter
# else
#define MBLabelAlignmentCenter UITextAlignmentCenter
# endif
# if __IPHONE_OS_VERSION_MIN_REQUIRED >= 70000
#define MB_TEXTSIZE(text, font) [text length] > 0 ? [text \
sizeWithAttributes:@{NSFontAttributeName:font}] : CGSizeZero;
# else
#define MB_TEXTSIZE(text, font) [text length] > 0 ? [text sizeWithFont:font] : CGSizeZero;
# endif这样就可以：
label.textAlignment = MBLabelAlignmentCenter;//设置居中。这是一种不错的方法。比如以前我在OpenShare中遇到的 containsString的问题：
[url.absoluteString containsString:@"//safepay/"]//iOS8的API
[url.absoluteString rangeOfString:@"//safepay/"].location != NSNotFound//iOS7的API这样我们也可以用宏，在NSString(Custom)中扩展containsString，来保持API一致。
在drawRect中画UI，通过kvo更新
比如MBBarProgressView:UIView整个UI是通过- (void)drawRect:(CGRect)rect中的CGContextFillPath类似方法画出来的。进度通过@property (nonatomic, assign) float progres来设置。而在drawRect中通过progres来控制画出来的样子。如果只有一个progres参数控制，我们可以在setter中：
-(void)setProgres:(float)prog{
_progress.prog;
[self setNeedsDisplay];//更新UI
}但是如果，我们是通过很多属性来控制的，一个个的在setter里面「hook」就不方便了。这时候我们可以用KVO：
- (void)registerForKVO {
for (NSString *keyPath in [self observableKeypaths]) {
[self addObserver:self forKeyPath:keyPath options:NSKeyValueObservingOptionNew context:NULL];
}
}
- (void)unregisterFromKVO {
for (NSString *keyPath in [self observableKeypaths]) {
[self removeObserver:self forKeyPath:keyPath];
}
}
- (NSArray *)observableKeypaths {
return [NSArray arrayWithObjects:@"mode", @"customView", @"labelText", @"labelFont", @"labelColor",
@"detailsLabelText", @"detailsLabelFont", @"detailsLabelColor", @"progress", @"activityIndicatorColor", nil];
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if (![NSThread isMainThread]) {
[self performSelectorOnMainThread:@selector(updateUIForKeypath:) withObject:keyPath waitUntilDone:NO];
} else {
[self updateUIForKeypath:keyPath];
}
}
- (void)updateUIForKeypath:(NSString *)keyPath {
//setter hook中的设置
if ([keyPath isEqualToString:@"mode"] || [keyPath isEqualToString:@"customView"] ||
[keyPath isEqualToString:@"activityIndicatorColor"]) {
[self updateIndicators];
} else if ([keyPath isEqualToString:@"labelText"]) {
label.text = self.labelText;
} else if ([keyPath isEqualToString:@"labelFont"]) {
label.font = self.labelFont;
} else if ([keyPath isEqualToString:@"labelColor"]) {
label.textColor = self.labelColor;
} else if ([keyPath isEqualToString:@"detailsLabelText"]) {
detailsLabel.text = self.detailsLabelText;
} else if ([keyPath isEqualToString:@"detailsLabelFont"]) {
detailsLabel.font = self.detailsLabelFont;
} else if ([keyPath isEqualToString:@"detailsLabelColor"]) {
detailsLabel.textColor = self.detailsLabelColor;
} else if ([keyPath isEqualToString:@"progress"]) {
if ([indicator respondsToSelector:@selector(setProgress:)]) {
[(id)indicator setValue:@(progress) forKey:@"progress"];
}
return;
}
[self setNeedsLayout];
[self setNeedsDisplay];//更新UI
}这样hook setter方法，更方便。在MBProgressHUD.m中MBProgressHUD : UIView、MBRoundProgressView : UIView 、MBBarProgressView : UIView中更新UI全是用的KVO的方法。
屏幕旋转
因为drawRect的时候已经考虑到宽度和高度了，所以屏幕旋转之后，只需要[self setNeedsDisplay]即可。
- (void)registerForNotifications {
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc addObserver:self selector:@selector(statusBarOrientationDidChange:)
name:UIApplicationDidChangeStatusBarOrientationNotification object:nil];
}
- (void)unregisterFromNotifications {
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc removeObserver:self name:UIApplicationDidChangeStatusBarOrientationNotification object:nil];
}
- (void)statusBarOrientationDidChange:(NSNotification *)notification {
UIView *superview = self.superview;
if (!superview) {
return;
} else {
[self updateForCurrentOrientationAnimated:YES];
}
}
- (void)updateForCurrentOrientationAnimated:(BOOL)animated {
// Stay in sync with the superview in any case
if (self.superview) {
self.bounds = self.superview.bounds;
[self setNeedsDisplay];
}
//iOS8之前只有window的第一个view能获得到roate事件，否则需要自己实现：
//via http://stackoverflow.com/questions/14704273/uiview-added-on-top-of-window-does-not-rotate-on-ios
// Not needed on iOS 8+, compile out when the deployment target allows,
// to avoid sharedApplication problems on extension targets
# if __IPHONE_OS_VERSION_MIN_REQUIRED < 80000
// Only needed pre iOS 7 when added to a window
BOOL iOS8OrLater = kCFCoreFoundationVersionNumber >= kCFCoreFoundationVersionNumber_iOS_8_0;
if (iOS8OrLater || ![self.superview isKindOfClass:[UIWindow class]]) return;
UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
CGFloat radians = 0;
if (UIInterfaceOrientationIsLandscape(orientation)) {
if (orientation == UIInterfaceOrientationLandscapeLeft) { radians = -(CGFloat)M_PI_2; }
else { radians = (CGFloat)M_PI_2; }
// Window coordinates differ!
self.bounds = CGRectMake(0, 0, self.bounds.size.height, self.bounds.size.width);
} else {
if (orientation == UIInterfaceOrientationPortraitUpsideDown) { radians = (CGFloat)M_PI; }
else { radians = 0; }
}
rotationTransform = CGAffineTransformMakeRotation(radians);
if (animated) {
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.3];
}
[self setTransform:rotationTransform];
if (animated) {
[UIView commitAnimations];
}
# endif
}执行block的时候显示
- (IBAction)showUsingBlocks:(id)sender {
# if NS_BLOCKS_AVAILABLE
MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView:self.navigationController.view];
[self.navigationController.view addSubview:hud];
hud.labelText = @"With a block";
[hud showAnimated:YES whileExecutingBlock:^{
[self myTask];
} completionBlock:^{
[hud removeFromSuperview];
[hud release];
}];
# endif
}
- (IBAction)showOnWindow:(id)sender {
// The hud will dispable all input on the window
HUD = [[MBProgressHUD alloc] initWithView:self.view.window];
[self.view.window addSubview:HUD];
HUD.delegate = self;
HUD.labelText = @"Loading";
[HUD showWhileExecuting:@selector(myTask) onTarget:self withObject:nil animated:YES];
}这个方法是非常有用的，可以直接省略hide和show的调用。而且逻辑也清晰。对于网络请求，我们也可以用这种思路，封装一下。
- (void)showAnimated:(BOOL)animated whileExecutingBlock:(dispatch_block_t)block onQueue:(dispatch_queue_t)queue
completionBlock:(MBProgressHUDCompletionBlock)completion {
self.taskInProgress = YES;
self.completionBlock = completion;
dispatch_async(queue, ^(void) {
block();
dispatch_async(dispatch_get_main_queue(), ^(void) {
[self cleanUp];
});
});
[self show:animated];
}
- (void)showWhileExecuting:(SEL)method onTarget:(id)target withObject:(id)object animated:(BOOL)animated {
methodForExecution = method;
targetForExecution = MB_RETAIN(target);
objectForExecution = MB_RETAIN(object);
// Launch execution in new thread
self.taskInProgress = YES;
[NSThread detachNewThreadSelector:@selector(launchExecution) toTarget:self withObject:nil];
// Show HUD view
[self show:animated];
}不得不说，把block当参数，程序设计方便很多。
MBProgressHUD使用
为了方便，MBProgressHUD提供了两类API：
- 类方法
- 实例是方法
类方法hide的时候，会找出所有MBProgressHUD，然后hide。+ (NSUInteger)hideAllHUDsForView:(UIView *)view animated:(BOOL)animated