这两天刚好项目上有一个头像拼接的需求，想必做即时通讯的很多都有这样的需求吧，所以就研究了一下微信的规则实现了一下。
效果如下

QQ20160929-0@2x.png

代码

/**
头像拼接
 @param array        图片数组
 @param size         图片大小
 @param cornerRadius 圆角半径

 @return <#return value description#>
 */
-(UIImage *)imageCompose:(NSArray *)array size:(CGSize)size cornerRadius:(CGFloat)cornerRadius
{
    if(array.count)
    {
        //开启一个图片上下文
        UIGraphicsBeginImageContextWithOptions(size, NO, [UIScreen mainScreen].scale) ;
        
        //添加裁剪路径
        UIBezierPath *clippath=[UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, size.width, size.height) cornerRadius:cornerRadius];
        [clippath addClip];
        
        //绘制背景矩形
        UIBezierPath *path=[UIBezierPath bezierPathWithRect:CGRectMake(0, 0, size.width, size.height)];
        [[UIColor lightGrayColor] setFill];
        [path fill];
        
       
        NSInteger count=array.count;
        if(count>9)
            count=9;
        
        //最大列数
        NSInteger max_col=3;
        //最大行数
        NSInteger max_row=3;
        //列数
        NSInteger column=ceil(count/2.0);
        if(column>max_col)
            column=max_col;
        else if (column<1)
            column=1;
        //行数
        NSInteger row=ceil(count/(CGFloat)column);
        if(row>max_row)
            row=max_row;
        
        
        
        if(row<1)
            row=1;
        
        //每个头像间的间距
        CGFloat margin=2;
        CGFloat imgsize=(size.width-(MAX(column, row)+1)*margin)/MAX(column, row);
        
        //每一行的列数
        NSInteger rowcount=ceil(count/(CGFloat)row);
        NSInteger k=0;
        for (int i =0; i<row; i++) {
            
            CGFloat rowmargin=(size.height-imgsize*row-margin*(MAX(row-1, 1)))/(CGFloat)row;
            //每一行的y值
            CGFloat y=i*imgsize+(i+1)*rowmargin;
            if(i>0)
                y=rowmargin+i*imgsize+i*margin;
            if(count<row*column&&i==0)
            {
                //第一行的列数
                NSInteger count1=rowcount-(row*column-count);
                CGFloat margin1=(size.width-imgsize*count1-margin*MAX(count1-1, 1))/2.0;
                for (int j=0; j<count1; j++) {
                    UIImage *img=array[k];
                    CGFloat x=margin1;
                    if(j>0)
                        x=margin1+j*imgsize+j*margin;
                    [img drawInRect:CGRectMake(x,y, imgsize, imgsize)];
                    k++;
                }
            }
            else
            {
                CGFloat margin1=(size.width-imgsize*rowcount)/(rowcount+1);
                for (int j=0; j<rowcount; j++) {
                    UIImage *img=array[k];
                    [img drawInRect:CGRectMake(j*imgsize+(j+1)*margin1, y, imgsize, imgsize)];
                    k++;
                }
            }

           
        }
        UIImage *newimge=UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        return newimge;

    }
    return nil;
}

• 调用

 NSMutableArray *imgs=[NSMutableArray array];
    [imgs addObject:[UIImage imageNamed:@"al1.jpg"]];
    [imgs addObject:[UIImage imageNamed:@"al2.jpg"]];
    [imgs addObject:[UIImage imageNamed:@"al3.jpg"]];
    [imgs addObject:[UIImage imageNamed:@"al4.jpg"]];
    [imgs addObject:[UIImage imageNamed:@"al5.jpg"]];
    [imgs addObject:[UIImage imageNamed:@"al6.jpg"]];
    [imgs addObject:[UIImage imageNamed:@"al7.jpg"]];
    [imgs addObject:[UIImage imageNamed:@"al8.jpg"]];
    [imgs addObject:[UIImage imageNamed:@"al9.jpg"]];
    UIImage *img=[self imageCompose:imgs size:CGSizeMake(100, 100) cornerRadius:10];
    self.imgv.image=img;