多图生成一张图片，给图片添加文字

#pragma mark--------------规律的图片数组生成一张图--------------------------
/**
 *  <#Description#>
 *
 *  @param imageArr 图片数组
 *  @param imageV   imageView的尺寸
 *
 *  @return 处理过后的image
 */
- (UIImage *)addImage:(NSArray *)imageArr toImageV:(UIImageView *)imageV {
    
    UIGraphicsBeginImageContext(imageV.frame.size);
    for (int a=0; a<imageArr.count; a++) {
        // Draw image1
        [imageArr[a] drawInRect:CGRectMake(0, a * 300, imageV.frame.size.width, 300)];
    }

    
    UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return [self watermarkImage:resultingImage withText:@"这就是水印"];
}

#pragma mark--------------不规律的图片数组生成一张图--------------------------
/**
 *  <#Description#>
 *
 *  @param image1 图片1
 *  @param image2 图片2
 *
 *  @return 将图片2放在图片1上返回
 */
- (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2 {
    UIGraphicsBeginImageContext(image1.size);
    
    // Draw image1
    [image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];
    
    // Draw image2
    [image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];
    
    UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    return resultingImage;
}

#pragma mark--------------给图片绘制文字--------------------------
/**
 *  <#Description#>
 *
 *  @param img  需要处理的图片
 *  @param text 添加的文字
 *
 *  @return 处理过后的图片
 */
- (UIImage *)watermarkImage:(UIImage *)img withText:(NSString *)text{
    
    //1.获取上下文
    
    UIGraphicsBeginImageContext(img.size);
    
    //2.绘制图片
    
    [img drawInRect:CGRectMake(0, 0, img.size.width, img.size.height)];
    
    //3.绘制水印文字
    
    CGRect rect = CGRectMake(0,20, img.size.width, 20);
    
    NSMutableParagraphStyle *style = [[NSMutableParagraphStyle defaultParagraphStyle] mutableCopy];
    
    style.alignment = NSTextAlignmentCenter;
    
    //文字的属性
    
    NSDictionary *dic = @{
                          
                          NSFontAttributeName:[UIFont systemFontOfSize:18],
                          
                          NSParagraphStyleAttributeName:style,
                          
                          NSForegroundColorAttributeName:[UIColor whiteColor]
                          
                          };
    
    //将文字绘制上去
    
    [text drawInRect:rect withAttributes:dic];
    
    //4.获取绘制到得图片
    
    UIImage *watermarkImage = UIGraphicsGetImageFromCurrentImageContext();
    
    //5.结束图片的绘制
    
    UIGraphicsEndImageContext();
    
    return watermarkImage;
}

#pragma mark--------------将文字准换成图片--------------------------
#define CONTENT_MAX_WIDTH   300.0f

-(UIImage *)imageFromText:(NSArray*) arrContent withFont: (CGFloat)fontSize
{
    // set the font type and size
    UIFont *font = [UIFont systemFontOfSize:fontSize];
    NSMutableArray *arrHeight = [[NSMutableArray alloc] initWithCapacity:arrContent.count];
    
    CGFloat fHeight = 0.0f;
    for (NSString *sContent in arrContent) {
        CGSize stringSize = [sContent sizeWithFont:font constrainedToSize:CGSizeMake(CONTENT_MAX_WIDTH, 10000) lineBreakMode:UILineBreakModeWordWrap];
        [arrHeight addObject:[NSNumber numberWithFloat:stringSize.height]];
        
        fHeight += stringSize.height;
    }
    
    
    CGSize newSize = CGSizeMake(CONTENT_MAX_WIDTH+20, fHeight+50);
    
    UIGraphicsBeginImageContextWithOptions(newSize,NO,0.0);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextSetCharacterSpacing(ctx, 10);
    CGContextSetTextDrawingMode (ctx, kCGTextFillStroke);
    CGContextSetRGBFillColor (ctx, 0.1, 0.2, 0.3, 1); // 6
    CGContextSetRGBStrokeColor (ctx, 0, 0, 0, 1);
    
    int nIndex = 0;
    CGFloat fPosY = 20.0f;
    for (NSString *sContent in arrContent) {
        NSNumber *numHeight = [arrHeight objectAtIndex:nIndex];
        CGRect rect = CGRectMake(10, fPosY, CONTENT_MAX_WIDTH , [numHeight floatValue]);
        
        
        [sContent drawInRect:rect withFont:font lineBreakMode:UILineBreakModeWordWrap alignment:UITextAlignmentLeft];
        
        fPosY += [numHeight floatValue];
        nIndex++;
    }
    // transfer image
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
    
}

注：转载请注明出处，写的不好的地方请大家多多包含。