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当我们在请求网络时加载页面时有个动作效果，效果如下：
源代码可以网上找开源项目Coding.net，上面的效果原理为两张图片组合，外面那个则为动画转动，里面的图标则是透明度的变化；主要代码如下：
1：把它封装在EaseLoadingView里面
@interface EaseLoadingView : UIView @property (strong, nonatomic) UIImageView *loopView, *monkeyView; @property (assign, nonatomic, readonly) BOOL isLoading; - (void)startAnimating; - (void)stopAnimating; @end
@interface EaseLoadingView () @property (nonatomic, assign) CGFloat loopAngle, monkeyAlpha, angleStep, alphaStep; @end @implementation EaseLoadingView - (instancetype)initWithFrame:(CGRect)frame{ self = [super initWithFrame:frame]; if (self) { self.backgroundColor = [UIColor clearColor]; _loopView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"loading_loop"]]; _monkeyView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"loading_monkey"]]; [_loopView setCenter:self.center]; [_monkeyView setCenter:self.center]; [self addSubview:_loopView]; [self addSubview:_monkeyView]; [_loopView mas_makeConstraints:^(MASConstraintMaker *make) { make.center.equalTo(self); }]; [_monkeyView mas_makeConstraints:^(MASConstraintMaker *make) { make.center.equalTo(self); }]; _loopAngle = 0.0; _monkeyAlpha = 1.0; _angleStep = 360/3; _alphaStep = 1.0/3.0; } return self; } - (void)startAnimating{ self.hidden = NO; if (_isLoading) { return; } _isLoading = YES; [self loadingAnimation]; } - (void)stopAnimating{ self.hidden = YES; _isLoading = NO; } - (void)loadingAnimation{ static CGFloat duration = 0.25f; _loopAngle += _angleStep; if (_monkeyAlpha >= 1.0 || _monkeyAlpha <= 0.0) { _alphaStep = -_alphaStep; } _monkeyAlpha += _alphaStep; [UIView animateWithDuration:duration delay:0.0 options:UIViewAnimationOptionCurveLinear animations:^{ CGAffineTransform loopAngleTransform = CGAffineTransformMakeRotation(_loopAngle * (M_PI / 180.0f)); _loopView.transform = loopAngleTransform; _monkeyView.alpha = _monkeyAlpha; } completion:^(BOOL finished) { if (_isLoading && [self superview] != nil) { [self loadingAnimation]; }else{ [self removeFromSuperview]; _loopAngle = 0.0; _monkeyAlpha = 1,0; _alphaStep = ABS(_alphaStep); CGAffineTransform loopAngleTransform = CGAffineTransformMakeRotation(_loopAngle * (M_PI / 180.0f)); _loopView.transform = loopAngleTransform; _monkeyView.alpha = _monkeyAlpha; } }]; } @end
注意loadingAnimation这里面有动作的处理及透明度的处理，当停止加载后把它自个从当前的视图去除；
2：UIView (Common)在UIView扩展类里
#pragma mark LoadingView @property (strong, nonatomic) EaseLoadingView *loadingView; - (void)beginLoading; - (void)endLoading; @end
- (void)setLoadingView:(EaseLoadingView *)loadingView{ [self willChangeValueForKey:@"LoadingViewKey"]; objc_setAssociatedObject(self, &LoadingViewKey, loadingView, OBJC_ASSOCIATION_RETAIN_NONATOMIC); [self didChangeValueForKey:@"LoadingViewKey"]; } - (EaseLoadingView *)loadingView{ return objc_getAssociatedObject(self, &LoadingViewKey); } - (void)beginLoading{ for (UIView *aView in [self.blankPageContainer subviews]) { if ([aView isKindOfClass:[EaseBlankPageView class]] && !aView.hidden) { return; } } if (!self.loadingView) { //初始化LoadingView self.loadingView = [[EaseLoadingView alloc] initWithFrame:self.bounds]; } [self addSubview:self.loadingView]; [self.loadingView mas_makeConstraints:^(MASConstraintMaker *make) { make.self.edges.equalTo(self); }]; [self.loadingView startAnimating]; } - (void)endLoading{ if (self.loadingView) { [self.loadingView stopAnimating]; } }
注意：cocoa的KVO模型中，有两种通知观察者的方式，自动通知和手动通知。顾名思义，自动通知由cocoa在属性值变化时自动通知观察者，而手动通知需要在值变化时调用 willChangeValueForKey:和didChangeValueForKey: 方法通知调用者。
3：使用页面调用
- (void)sendRequest{ [self.view beginLoading]; __weak typeof(self) weakSelf = self; [[Coding_NetAPIManager sharedManager] request_CodeFile:_myCodeFile withPro:_myProject andBlock:^(id data, NSError *error) { [weakSelf.view endLoading]; if (data) { weakSelf.myCodeFile = data; [weakSelf refreshCodeViewData]; } [weakSelf.view configBlankPage:EaseBlankPageTypeView hasData:(data != nil) hasError:(error != nil) reloadButtonBlock:^(id sender) { [weakSelf sendRequest]; }]; }]; }
其中[self.view beginLoading]跟[weakSelf.view endLoading]就可以调用动画效果；
补充：另一种是有很多不同的图片组成的动画效果，可以用每一张图片然后FOR遍历组成出动作效果；
//设置普通状态的动画图片 NSMutableArray *idleImages = [NSMutableArray array]; for (NSUInteger i = 1; i<=60; ++i) { UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"dropdown_anim__000%zd",i]]; [idleImages addObject:image]; [idleImages addObject:image]; }
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原文地址：http://www.cnblogs.com/wujy/p/4714053.html
