Android内存优化之封装九宫格

<span style="font-family:Arial;font-size:14px;">//数据源协议
@protocol JRMainScrollDataSource <NSObject>
//获取总的数量
- (NSInteger) numberOfItems;

//获取列的数量
- (NSInteger) numberOfColumsOfRow;
//获取item
- (UIView *) mainScrollView:(JRMainScrollView *)mainScrollView itemAtIndex:(NSInteger) index;
@end</span>

<span style="font-family:Arial;font-size:14px;">//属性协议
@protocol JRMainScrollDelegate <NSObject>
@optional
//获取高度
- (CGFloat)  heightForItemAtView:(JRMainScrollView *) mainScrollView;

//获取宽度
- (CGFloat)  widthForItemAtView:(JRMainScrollView *) mainScrollView;

//获取间距
- (CGFloat) mainScrollView:(JRMainScrollView *)mainScrollView spaceForItemWithType:(kJRMainScrollItemSpace)type;
@end</span>

<span style="font-family:Arial;font-size:14px;">typedef enum{
    kJRMainScrollItemLeftSpace,
    kJRMainScrollItemTopSpace
} kJRMainScrollItemSpace;</span>

<span style="font-family:Arial;font-size:14px;">//加载子视图
- (void)_loadSubViews{
    //获取总个数和列数
    NSInteger totalItems=[self.jrDataSource numberOfItems];
    NSInteger colum=[self.jrDataSource numberOfColumsOfRow];

    //获取宽度和高度
    CGFloat itemWidth=[self.jrDelegate widthForItemAtView:self];
    CGFloat itemHeigt=[self.jrDelegate heightForItemAtView:self];

    //获取上下间距
    CGFloat leftSpace=[self.jrDelegate mainScrollView:self spaceForItemWithType:kJRMainScrollItemLeftSpace];
    CGFloat topSpace=[self.jrDelegate mainScrollView:self spaceForItemWithType:kJRMainScrollItemTopSpace];

    CGFloat space=(kWidth-2*leftSpace-colum*itemWidth)/(colum-1)+itemWidth;

    for (int i=0;i<totalItems;i++) {
        int clo=i%colum;
        int row=i/colum;
        CGRect frame=CGRectMake(leftSpace+clo*space, 20+row*(itemHeigt+topSpace), itemWidth, itemHeigt);
        [self.array addObject:[NSValue valueWithCGRect:frame]];    
    }
self.contentSize=CGSizeMake(0, CGRectGetMaxY([[self.array lastObject] CGRectValue]));
    self.showsVerticalScrollIndicator=NO;

}</span>

<span style="font-family:Arial;font-size:14px;">-(void)layoutSubviews{
    [super layoutSubviews];

    //循环便利获取在屏幕中的frame
    for (int i=0;i<self.array.count;i++) {

        UIView * tempView=(UIView *)self.current[@(i)];

        CGRect rect=[self.array[i] CGRectValue];
        if ([self isInScreenWith:rect]) {
            if(!tempView){//字典里没有的才需要重重新加载
                UIView *view=[self.jrDataSource mainScrollView:self itemAtIndex:i];
                view.frame=rect;
                [self.current setObject:view forKey:@(i)];
                [self addSubview:view];
            }

        }else if(tempView){//如果存在字典而且不在视线内部的则移除
            [self.current removeObjectForKey:@(i)];
            [tempView removeFromSuperview];
            [self.pool addObject:tempView];
        }  
    }

//判断是不是在视野内部，其中有两种情况，Y值在屏幕内部，或者MAXY值在屏幕内部
- (BOOL) isInScreenWith:(CGRect) frame{
    CGFloat setMiny=self.contentOffset.y;
    CGFloat setMaxy=self.contentOffset.y+kHeight;    
    BOOL condition1=frame.origin.y>=setMiny&&frame.origin.y<=setMaxy;
    BOOL condition2=CGRectGetMaxY(frame)>=setMiny&&CGRectGetMaxY(frame)<=setMaxy;

    if(condition1||condition2){
        return YES;
    }

    return NO;
        }</span>

<span style="font-family:Arial;font-size:14px;">/** 存放frame*/
@property(nonatomic,strong) NSMutableArray * array;
/** 存放当前显示的对象*/
@property(nonatomic,strong) NSMutableDictionary * current;
/** 存放缓冲池对象*/
@property(nonatomic,strong) NSMutableSet * pool;
/**
 *  获取重复利用的对象
 *
 *  @param identy <#identy description#>
 *
 *  @return <#return value description#>
 */
- (JRRectView *) dequeueReusedItemWithIdenty:(NSString *) identy{
    JRRectView * view=[self.pool anyObject];
    if (view!=nil) {
        [self.pool removeObject:view];
    }
    return view;
}</span>

<span style="font-family:Arial;font-size:14px;"> //加载所有数据
- (void) _loadSubviews{

    //1 增加滚动视图
    JRMainScrollView * mainScroll=[[JRMainScrollView alloc] initWithFrame:self.view.bounds];
    mainScroll.jrDataSource=self;
    mainScroll.jrDelegate=self;
    [mainScroll reloadViews];
    [self.view addSubview:mainScroll];

}
#pragma mark - 数据源方法
-(NSInteger)numberOfItems{
    return 132;
}

-(NSInteger) numberOfColumsOfRow{
    return 3;
}

-(UIView *) mainScrollView:(JRMainScrollView *)mainScrollView itemAtIndex:(NSInteger)index{

    JRRectView *cell=[mainScrollView dequeueReusedItemWithIdenty:@"test"];
    if (cell==nil) {
        cell=[[[NSBundle mainBundle] loadNibNamed:@"rect" owner:nil options:nil] lastObject];
    }

    cell.titleLabel.text=[NSString stringWithFormat:@"下载"];
    NSString * imageName=[NSString stringWithFormat:@"%d",arc4random_uniform(20)+256];
    UIImage *image=[UIImage imageNamed:imageName];
    cell.image.image=image;

    return cell;
}

#pragma mark - 代理方法

//获取高度
- (CGFloat)  heightForItemAtView:(JRMainScrollView *) mainScrollView{
   return 100;
}

//获取宽度
- (CGFloat)  widthForItemAtView:(JRMainScrollView *) mainScrollView{
    return 90;
}

//获取间距
- (CGFloat) mainScrollView:(JRMainScrollView *)mainScrollView spaceForItemWithType:(kJRMainScrollItemSpace)type{

    if (type==kJRMainScrollItemLeftSpace) {
        return 20;
    }else if (type==kJRMainScrollItemTopSpace){
        return 20;
    }
    return 20;

}</span>