渐变显示渐变消失的BackgroundView

效果如下：

源码：

BackgroundView.h 与 BackgroundView.m

//
//  BackgroundView.h
//  TestHUD
//
//  Created by YouXianMing on 14-9-30.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//#import <UIKit/UIKit.h>@interface BackgroundView : UIView@property (nonatomic, assign) NSTimeInterval  startDuration; // 动画开始时持续时间
@property (nonatomic, assign) NSTimeInterval  endDuration;   // 动画结束时持续时间- (instancetype)initInView:(UIView *)view;// 开始附加到view中
- (void)addToView;// 将自己从view中移除掉
- (void)removeSelf;@end

//
//  BackgroundView.m
//  TestHUD
//
//  Created by YouXianMing on 14-9-30.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//#import "BackgroundView.h"#ifdef DEBUG
#define BackgroundView_DLog(fmt, ...) NSLog((@"BackgroundView.m:%s:%d" fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__);
#else
#define BackgroundView_DLog(...)
#endif@interface BackgroundView ()@property (nonatomic, weak) UIView   *inView;@end@implementation BackgroundView- (instancetype)initInView:(UIView *)view
{self = [super initWithFrame:view.bounds];if (self) {_inView              = view;self.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5f];self.alpha           = 0;}return self;
}- (void)addToView
{// 添加到view中[_inView addSubview:self];// 开始执行动画NSTimeInterval duration = 0.2;if (_startDuration > 0) {duration = _startDuration;}[UIView animateWithDuration:duration animations:^{self.alpha = 1.f;}];
}- (void)removeSelf
{// 开始执行动画NSTimeInterval duration = 0.2;if (_endDuration > 0) {duration = _endDuration;}[UIView animateWithDuration:duration animations:^{self.alpha = 0.f;} completion:^(BOOL finished) {[self removeFromSuperview];}];
}- (void)dealloc
{BackgroundView_DLog(@" 安全释放");
}@end

category文件：

//
//  UIView+BackgroundView.h
//  BackgroundView
//
//  Created by YouXianMing on 14-10-3.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//#import <UIKit/UIKit.h>
#import "BackgroundView.h"typedef void (^ConfigBackgroundViewBlock)(BackgroundView *configView);@interface UIView (BackgroundView)- (void)showBackgroundViewAndConfig:(ConfigBackgroundViewBlock)block;
- (void)removeBackgroundView;@end

//
//  UIView+BackgroundView.m
//  BackgroundView
//
//  Created by YouXianMing on 14-10-3.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//#import "UIView+BackgroundView.h"#define TAG_DATA  0x3d2894@implementation UIView (BackgroundView)- (void)showBackgroundViewAndConfig:(ConfigBackgroundViewBlock)block
{if (self == nil) {return;}BackgroundView *backView = [[BackgroundView alloc] initInView:self];backView.tag = TAG_DATA;block(backView);[backView addToView];
}- (void)removeBackgroundView
{BackgroundView *backView = (BackgroundView *)[self viewWithTag:TAG_DATA];if (backView) {[backView removeSelf];}
}@end

使用的源码：

//
//  ViewController.m
//  BackgroundView
//
//  Created by YouXianMing on 14-10-3.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//#import "ViewController.h"
#import "UIView+BackgroundView.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {[super viewDidLoad];// 添加手势UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:selfaction:@selector(tapEvent:)];[self.view addGestureRecognizer:tap];UILabel *label      = [[UILabel alloc] initWithFrame:self.view.bounds];label.text          = @"YouXianMing";label.textAlignment = NSTextAlignmentCenter;label.font          = [UIFont fontWithName:@"HelveticaNeue-Thin" size:40.f];label.textColor     = [UIColor redColor];[self.view addSubview:label];
}- (void)tapEvent:(UITapGestureRecognizer *)tap
{// 显示[self.view showBackgroundViewAndConfig:^(BackgroundView *configView) {configView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.6];configView.startDuration = 0.4f;configView.endDuration   = 0.4f;}];// 延迟3s执行[self performSelector:@selector(affterDelay)withObject:nilafterDelay:3.f];
}- (void)affterDelay
{// 隐藏[self.view removeBackgroundView];
}@end

以下是需要注意的地方：