平常开发中对于启动页可能会有一些特别的要求，比如在启动页加动画或加一些按键可以响应事件等，最近项目中要在启动页增加版本号，因为版本号是不断的改变，所以要动态实现把它加到启动页上；在XCode上面配置的Launch Images Source或Launch Screen FIle(IOS8以上会优先调用这个作为启动项)都是保存一张静态图片；
原理：
其实原理也是很简单，启动页还是运用Launch Images Source的内容，然后在做一个视图在最上层，视图的背景用启动项的那张图，让人误以为还在启动中，启动页加载完成后，就显示这层视图，在2秒后再把这层视图删除，产生一个过度的假启动页效果；而我们自定义的动作就可以在这层视图上进行；下面将通过Coding.net的APP讲解这个功能；
一：创建一个视图EaseStartView
EaseStartView.h文件内容：
#import <UIKit/UIKit.h> @interface EaseStartView : UIView + (instancetype)startView; - (void)startAnimationWithCompletionBlock:(void(^)(EaseStartView *easeStartView))completionHandler; @end
EaseStartView.m文件内容：
#import "EaseStartView.h" #import <NYXImagesKit/NYXImagesKit.h> #import "StartImagesManager.h" @interface EaseStartView () @property (strong, nonatomic) UIImageView *bgImageView, *logoIconView; @property (strong, nonatomic) UILabel *descriptionStrLabel; @end @implementation EaseStartView + (instancetype)startView{ UIImage *logoIcon = [UIImage imageNamed:@"logo_coding_top"]; StartImage *st = [[StartImagesManager shareManager] randomImage]; return [[self alloc] initWithBgImage:st.image logoIcon:logoIcon descriptionStr:st.descriptionStr]; } - (instancetype)initWithBgImage:(UIImage *)bgImage logoIcon:(UIImage *)logoIcon descriptionStr:(NSString *)descriptionStr{ self = [super initWithFrame:kScreen_Bounds]; if (self) { //add custom code UIColor *blackColor = [UIColor blackColor]; self.backgroundColor = blackColor; _bgImageView = [[UIImageView alloc] initWithFrame:kScreen_Bounds]; _bgImageView.contentMode = UIViewContentModeScaleAspectFill; _bgImageView.alpha = 0.0; [self addSubview:_bgImageView]; [self addGradientLayerWithColors:@[(id)[blackColor colorWithAlphaComponent:0.4].CGColor, (id)[blackColor colorWithAlphaComponent:0.0].CGColor] locations:nil startPoint:CGPointMake(0.5, 0.0) endPoint:CGPointMake(0.5, 0.4)]; _logoIconView = [[UIImageView alloc] init]; _logoIconView.contentMode = UIViewContentModeScaleAspectFit; [self addSubview:_logoIconView]; _descriptionStrLabel = [[UILabel alloc] init]; _descriptionStrLabel.font = [UIFont systemFontOfSize:10]; _descriptionStrLabel.textColor = [UIColor colorWithWhite:1.0 alpha:0.5]; _descriptionStrLabel.textAlignment = NSTextAlignmentCenter; _descriptionStrLabel.alpha = 0.0; [self addSubview:_descriptionStrLabel]; [_descriptionStrLabel mas_makeConstraints:^(MASConstraintMaker *make) { make.centerX.equalTo(@[self, _logoIconView]); make.height.mas_equalTo(10); make.bottom.equalTo(self.mas_bottom).offset(-15); make.left.equalTo(self.mas_left).offset(20); make.right.equalTo(self.mas_right).offset(-20); }]; [_logoIconView mas_makeConstraints:^(MASConstraintMaker *make) { make.centerX.equalTo(self); make.top.mas_equalTo(kScreen_Height/7); make.width.mas_equalTo(kScreen_Width *2/3); make.height.mas_equalTo(kScreen_Width/4 *2/3); }]; [self configWithBgImage:bgImage logoIcon:logoIcon descriptionStr:descriptionStr]; } return self; } - (void)configWithBgImage:(UIImage *)bgImage logoIcon:(UIImage *)logoIcon descriptionStr:(NSString *)descriptionStr{ bgImage = [bgImage scaleToSize:[_bgImageView doubleSizeOfFrame] usingMode:NYXResizeModeAspectFill]; self.bgImageView.image = bgImage; self.logoIconView.image = logoIcon; self.descriptionStrLabel.text = descriptionStr; [self updateConstraintsIfNeeded]; } - (void)startAnimationWithCompletionBlock:(void(^)(EaseStartView *easeStartView))completionHandler{ [[UIApplication sharedApplication].keyWindow addSubview:self]; [[UIApplication sharedApplication].keyWindow bringSubviewToFront:self]; _bgImageView.alpha = 0.0; _descriptionStrLabel.alpha = 0.0; @weakify(self); [UIView animateWithDuration:2.0 animations:^{ @strongify(self); self.bgImageView.alpha = 1.0; self.descriptionStrLabel.alpha = 1.0; } completion:^(BOOL finished) { [UIView animateWithDuration:0.6 delay:0.3 options:UIViewAnimationOptionCurveEaseIn animations:^{ @strongify(self); [self setX:-kScreen_Width]; } completion:^(BOOL finished) { @strongify(self); [self removeFromSuperview]; if (completionHandler) { completionHandler(self); } }]; }]; } @end
其实本实例中最为关键的内容在方法startAnimationWithCompletionBlock里
[[UIApplication sharedApplication].keyWindow addSubview:self];
[[UIApplication sharedApplication].keyWindow bringSubviewToFront:self];
代码就是把这个视图设置成在最前的最上层，这样就可以盖住程序中的页面；
_bgImageView.alpha = 0.0; _descriptionStrLabel.alpha = 0.0;
这个是为了下面的动画做准备，若是直接用背景图可以把这两个都设置成0.99这样就不会有一闪的错觉；
@weakify(self); [UIView animateWithDuration:2.0 animations:^{ @strongify(self); self.bgImageView.alpha = 1.0; self.descriptionStrLabel.alpha = 1.0; } completion:^(BOOL finished) { [UIView animateWithDuration:0.6 delay:0.3 options:UIViewAnimationOptionCurveEaseIn animations:^{ @strongify(self); [self setX:-kScreen_Width]; } completion:^(BOOL finished) { @strongify(self); [self removeFromSuperview]; if (completionHandler) { completionHandler(self); } }]; }];
这边是动画效果，时间设置为2秒，因为这边第一个动画完还有一个左移出启动页的效果；当动画结束后就可以 [self removeFromSuperview];
二：调用启动页视图
在AppDelegate中的didFinishLaunchingWithOptions进行调用；
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; // Override point for customization after application launch. self.window.backgroundColor = [UIColor whiteColor]; //网络 [[AFNetworkActivityIndicatorManager sharedManager] setEnabled:YES]; [[AFNetworkReachabilityManager sharedManager] startMonitoring]; //设置导航条样式 [self customizeInterface]; [[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationFade]; if ([Login isLogin]) { [self setupTabViewController]; }else{ [UIApplication sharedApplication].applicationIconBadgeNumber = 0; [self setupIntroductionViewController]; } [self.window makeKeyAndVisible]; [FunctionIntroManager showIntroPage]; EaseStartView *startView = [EaseStartView startView]; @weakify(self); [startView startAnimationWithCompletionBlock:^(EaseStartView *easeStartView) { @strongify(self); //可以做其它事情 }]; return YES; }
注意，EaseStartView代码的位置是要放在最后面，因为要让它盖在最上层，就要后面加载，这样就可以盖在登录页面上面或者主页上；到这就已经可以成功启动页的效果；
三：下面实例为项目中用到的动态加载版本号到启动页上
#import "StartUpView.h" @interface StartUpView() @property (strong, nonatomic) UIImageView *bgImageView; @property (strong, nonatomic) UILabel *descriptionStrLabel; @end @implementation StartUpView + (instancetype)startView { UIImage *bgImage=kshamLaunchImage; return [[self alloc] initWithBgImage:bgImage]; } - (instancetype)initWithBgImage:(UIImage *)bgImage { self = [super initWithFrame:Main_Screen_Bounds]; if (self) { _bgImageView = [[UIImageView alloc] initWithFrame:Main_Screen_Bounds]; _bgImageView.contentMode = UIViewContentModeScaleAspectFill; _bgImageView.alpha = 0; _bgImageView.image=bgImage; [self addSubview:_bgImageView]; _descriptionStrLabel = [[UILabel alloc] init]; _descriptionStrLabel.font = [UIFont systemFontOfSize:15]; _descriptionStrLabel.textColor = [UIColor blackColor]; _descriptionStrLabel.textAlignment = NSTextAlignmentCenter; _descriptionStrLabel.alpha = 0; _descriptionStrLabel.text=[NSString stringWithFormat:@"版本号为:%@",appVersion]; [self addSubview:_descriptionStrLabel]; [_descriptionStrLabel mas_makeConstraints:^(MASConstraintMaker *make) { make.height.mas_equalTo(50); make.bottom.equalTo(self.mas_bottom).offset(-15); make.left.equalTo(self.mas_left).offset(20); make.right.equalTo(self.mas_right).offset(-20); }]; } return self; } - (void)startAnimationWithCompletionBlock:(void(^)(StartUpView *easeStartView))completionHandler{ [[UIApplication sharedApplication].keyWindow addSubview:self]; [[UIApplication sharedApplication].keyWindow bringSubviewToFront:self]; _bgImageView.alpha = 0.99; _descriptionStrLabel.alpha = 0.99; @weakify(self); [UIView animateWithDuration:2.0 animations:^{ @strongify(self); self.bgImageView.alpha = 1.0; self.descriptionStrLabel.alpha = 1.0; } completion:^(BOOL finished) { [self removeFromSuperview]; if (completionHandler) { completionHandler(self); } }]; } @end
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