多张照片合成1张

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    NSArray *imgArray = [[NSArray alloc] initWithObjects:
                         [UIImage imageNamed:@"1.jpg"],
                         [UIImage imageNamed:@"2.jpg"],
                         [UIImage imageNamed:@"3.jpg"],
                         [UIImage imageNamed:@"4.jpg"],
                         [UIImage imageNamed:@"5.jpg"],
                         nil];
    
    
    
    //imgPointArray中的数据为图片在合成后的图片后的x,y坐标。
    NSArray *imgPointArray = [[NSArray alloc] initWithObjects:
                              @"10", @"10",
                              @"20", @"20",
                              @"30", @"30",
                              @"40", @"40",
                              @"50", @"50",
                              nil];
    
    
    BOOL suc = [self mergedImageOnMainImage:[UIImage imageNamed:@"1.jpg"] WithImageArray:imgArray AndImagePointArray:imgPointArray];
    
    if (suc == YES) {
        NSLog(@"Images Successfully Mearged & Saved to Album");
    }
    else {
        NSLog(@"Images not Mearged & not Saved to Album");
    }

}
#pragma -mark -functions
//多张图片合成一张
- (BOOL) mergedImageOnMainImage:(UIImage *)mainImg WithImageArray:(NSArray *)imgArray AndImagePointArray:(NSArray *)imgPointArray
{
    
    UIGraphicsBeginImageContext(mainImg.size);
    
    [mainImg drawInRect:CGRectMake(0, 0, mainImg.size.width, mainImg.size.height)];
    int i = 0;
    for (UIImage *img in imgArray) {
        [img drawInRect:CGRectMake([[imgPointArray objectAtIndex:i] floatValue],
                                   [[imgPointArray objectAtIndex:i+1] floatValue],
                                   img.size.width,
                                   img.size.height)];
        
        i+=2;
    }
    
    CGImageRef NewMergeImg = CGImageCreateWithImageInRect(UIGraphicsGetImageFromCurrentImageContext().CGImage,
                                                          CGRectMake(0, 0, mainImg.size.width, mainImg.size.height));
    
    UIGraphicsEndImageContext();
    if (NewMergeImg == nil) {
        return NO;
    }
    else {
        UIImageWriteToSavedPhotosAlbum([UIImage imageWithCGImage:NewMergeImg], self, nil, nil);
        return YES;
    }
}