IOS第17天（1,Quartz2D图片水印）

#import "HMViewController.h"

@interface HMViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation HMViewController

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

UIImage *oldImage = [UIImage imageNamed:@"img"];

// 开启上下文
// size 新的图片大小
// opaque YES 不透明 NO 透明
UIGraphicsBeginImageContextWithOptions(oldImage.size, NO, 0.0);
[oldImage drawAtPoint:CGPointZero];

NSString *text =  @"我要高薪 ！";
NSDictionary *dict = @{
NSFontAttributeName : [UIFont systemFontOfSize:15],
NSForegroundColorAttributeName : [UIColor redColor]

};
[text drawAtPoint:CGPointMake(120, 170) withAttributes:dict];

// 获取新的图片
UIImage *newImage =  UIGraphicsGetImageFromCurrentImageContext();

// 关闭上下文
UIGraphicsEndImageContext();

_imageView.image = newImage;

// 把图片转换成png格式的二进制数据
NSData *data = UIImagePNGRepresentation(newImage);

// 写入桌面
[data writeToFile:@"/Users/apple/Desktop/newImage.png" atomically:YES];

}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end