[WEEX-241][iOS] add WXVideoComponent "poster" attribute

ios/sdk/WeexSDK/Sources/Component/WXVideoComponent.h

@@ -30,8 +30,10 @@ typedef NS_ENUM(NSInteger, WXPlaybackState) {
 @interface WXVideoView : UIView
 
 @property (nonatomic, copy) void (^playbackStateChanged)(WXPlaybackState state);
+@property (nonatomic, copy) void (^posterClickHandle)(void);
 
 - (void) setURL:(NSURL*)URL;
+- (void) setPosterURL:(NSURL *)posterURL;
 
 - (void) play;
 - (void) pause;

ios/sdk/WeexSDK/Sources/Component/WXVideoComponent.m

@@ -21,6 +21,7 @@
 #import "WXHandlerFactory.h"
 #import "WXURLRewriteProtocol.h"
 #import "WXSDKEngine.h"
+#import "WXImgLoaderProtocol.h"
 
 #import <AVFoundation/AVPlayer.h>
 #import <AVKit/AVPlayerViewController.h>
@@ -41,6 +42,9 @@ @interface WXVideoView()
 @property (nonatomic, strong) UIViewController* playerViewController;
 @property (nonatomic, strong) AVPlayerItem* playerItem;
 @property (nonatomic, strong) WXSDKInstance* weexSDKInstance;
+@property (nonatomic, strong) UIImageView *posterImageView;
+@property (nonatomic, strong) id<WXImageOperationProtocol> imageOperation;
+@property (nonatomic, assign) BOOL playerDidPlayed;
 
 @end
 
@@ -188,6 +192,24 @@ - (void)setURL:(NSURL *)URL
     }
 }
 
+- (void)setPosterURL:(NSURL *)posterURL {
+    if (!posterURL) {
+        return;
+    }
+
+    [self cancelImage];
+    __weak typeof(self) weakSelf = self;
+    weakSelf.imageOperation = [[self imageLoader] downloadImageWithURL:posterURL.absoluteString imageFrame:self.posterImageView.frame userInfo:nil completed:^(UIImage *image, NSError *error, BOOL finished) {
+        dispatch_async(dispatch_get_main_queue(), ^{
+            __strong typeof(self) strongSelf = weakSelf;
+            if (!error) {
+                strongSelf.posterImageView.image = image;
+                strongSelf.posterImageView.hidden = strongSelf.playerDidPlayed;
+            }
+        });
+    }];
+}
+
 - (void)playFinish
 {
     if (_playbackStateChanged)
@@ -203,6 +225,7 @@ - (void)playFinish
 
 - (void)play
 {
+    _posterImageView.hidden = YES;
     if ([self greater8SysVer]) {
         AVPlayerViewController *AVVC = (AVPlayerViewController*)_playerViewController;
 
@@ -224,12 +247,47 @@ - (void)pause
     }
 }
 
+- (void)posterTapHandler {
+    if (self.posterClickHandle) {
+        self.posterClickHandle();
+    }
+}
+
+- (UIImageView *)posterImageView {
+    if (!_posterImageView) {
+        _posterImageView = [[UIImageView alloc] initWithFrame:self.bounds];
+        _posterImageView.userInteractionEnabled = YES;
+        [_posterImageView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(posterTapHandler)]];
+        _posterImageView.hidden = YES;
+        [self addSubview:_posterImageView];
+        [self bringSubviewToFront:_posterImageView];
+    }
+    return _posterImageView;
+}
+
+- (id<WXImgLoaderProtocol>)imageLoader
+{
+    static id<WXImgLoaderProtocol> imageLoader;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        imageLoader = [WXHandlerFactory handlerForProtocol:@protocol(WXImgLoaderProtocol)];
+    });
+    return imageLoader;
+}
+
+- (void)cancelImage
+{
+    [_imageOperation cancel];
+    _imageOperation = nil;
+}
+
 @end
 
 @interface WXVideoComponent()
 
 @property (nonatomic, weak) WXVideoView *videoView;
 @property (nonatomic, strong) NSURL *videoURL;
+@property (nonatomic, strong) NSURL *posterURL;
 @property (nonatomic) BOOL autoPlay;
 @property (nonatomic) BOOL playStatus;
 
@@ -252,6 +310,9 @@ - (instancetype)initWithRef:(NSString *)ref type:(NSString *)type styles:(NSDict
         if ([attributes[@"playStatus"] compare:@"pause" options:NSCaseInsensitiveSearch] == NSOrderedSame) {
             _playStatus = false;
         }
+        if (attributes[@"poster"]) {
+            _posterURL = [NSURL URLWithString: attributes[@"poster"]];
+        }
     }
     return self;
 }
@@ -268,6 +329,7 @@ -(void)viewDidLoad
 {
     _videoView = (WXVideoView *)self.view;
     [_videoView setURL:_videoURL];
+    [_videoView setPosterURL:_posterURL];
     if (_playStatus) {
         [_videoView play];
     } else {
@@ -277,6 +339,9 @@ -(void)viewDidLoad
         [_videoView play];
     }
     __weak __typeof__(self) weakSelf = self;
+    _videoView.posterClickHandle = ^{
+        [weakSelf.videoView play];
+    };
     _videoView.playbackStateChanged = ^(WXPlaybackState state) {
         NSString *eventType = nil;
         switch (state) {
@@ -319,6 +384,10 @@ -(void)updateAttributes:(NSDictionary *)attributes
         _playStatus = false;
         [_videoView pause];
     }
+    if (attributes[@"poster"]) {
+        _posterURL = [NSURL URLWithString: attributes[@"poster"]];
+        [_videoView setPosterURL:_posterURL];
+    }
 }
 
 @end