將字符串添加到圖形上下文的方法- (void)drawAtPoint:(CGPoint)point withAttributes:(nullable NSDictionary<NSAttributedStringKey, id> *)attrs- (void)drawInRect:(CGRect)rect withAttributes:(nullable NSDictionary<NSAttributedStringKey, id> *)attrs將字符串添加到圖形上下文的方法- (void)drawAtPoint:(CGPoint)point;               // mode = kCGBlendModeNormal, alpha = 1.0- (void)drawAtPoint:(CGPoint)point blendMode:(CGBlendMode)blendMode alpha:(CGFloat)alpha; - (void)drawInRect:(CGRect)rect;                // mode = kCGBlendModeNormal, alpha = 1.0- (void)drawInRect:(CGRect)rect blendMode:(CGBlendMode)blendMode alpha:(CGFloat)alpha;

//1. 要手動創(chuàng)建一個位圖上下文,創(chuàng)建位圖上下文時，要指定大小,指定的大小，決定著生成圖片的尺寸是多大void UIGraphicsBeginImageContext(CGSize size); //2. 把內(nèi)容繪制到上下文當中//2.1繪制原始圖片//2.2繪制文字//2.3繪制logo //3. 從上下文當中生成一張圖片，把上下文當中繪制的所有內(nèi)容合成在一起生成一張跟上下文尺度一樣的圖片UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext() ; //4.手動創(chuàng)建的上下文一定要手動去銷毀掉UIGraphicsEndImageContext() ;

#import <UIKit/UIKit.h> NS_ASSUME_NONNULL_BEGIN @interface SWWaterMarkImage : UIImage-(UIImage *)WaterImageWithImage:(UIImage *)image ImageLogo:(UIImage *)imageLogo title:(NSString *)string ;+(UIImage *)WaterImageWithImage:(UIImage *)image ImageLogo:(UIImage *)imageLogo title:(NSString *)string ;@end NS_ASSUME_NONNULL_END

@implementation SWWaterMarkImage-(UIImage *)WaterImageWithImage:(UIImage *)image ImageLogo:(UIImage *)imageLogo title:(NSString *)string {   //1.要手動創(chuàng)建一個位圖上下文 UIGraphicsBeginImageContext(image.size) ;   //2.繪制到內(nèi)容上下文中 //原始圖片渲染 [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];   //文字 NSDictionary *attributeDict = @{         NSFontAttributeName : [UIFont systemFontOfSize:20.f],         NSForegroundColorAttributeName:[UIColor whiteColor],//         NSBackgroundColorAttributeName :[UIColor redColor]         } ; CGRect rectSize = [string boundingRectWithSize:CGSizeMake(MAXFLOAT, 30) options:NSStringDrawingUsesDeviceMetrics attributes:attributeDict context:nil] ; CGFloat x = image.size.width - rectSize.size.width - 10 ; CGFloat y = image.size.height - 30 ; [string drawAtPoint:CGPointMake(x, y) withAttributes:attributeDict] ;   //logo圖片 CGFloat waterW = 30; CGFloat waterH = 30; CGFloat waterX = x - waterW - 10 ; CGFloat waterY = y - 3 ; [imageLogo drawInRect:CGRectMake(waterX, waterY, waterW, waterH)] ;  //3.從當前的上下文當中生成一張新的圖片 UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext() ;   //4.手動創(chuàng)建的上下文一定要手動去銷毀掉 UIGraphicsEndImageContext() ;   return newImage ;} +(UIImage *)WaterImageWithImage:(UIImage *)image ImageLogo:(UIImage *)imageLogo title:(NSString *)string { return [[self alloc]WaterImageWithImage:image ImageLogo:imageLogo title:string] ;}@end

#import "ViewController.h"#import "SWWaterMarkImage.h"@interface ViewController ()@property(nonatomic,strong)UIImageView *imageView ;@end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad];   //生成一張加水印圖片步驟： /*  可以在任何方法中生成圖片,不一定在drawRect:方法中生成  1.要手動創(chuàng)建一個位圖上下文,創(chuàng)建位圖上下文時，要指定大小,指定的大小，決定著生成圖片的尺寸是多大  2.把內(nèi)容繪制到上下文當中  3.從上下文當中生成一張圖片，把上下文當中繪制的所有內(nèi)容合成在一起生成一張跟上下文尺度一樣的圖片  4.手動創(chuàng)建的上下文一定要手動去銷毀掉  */}-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{ UIImage *newImage = [SWWaterMarkImage WaterImageWithImage:[UIImage imageNamed:@"18d8bc3eb13533fa65021ddba5d3fd1f40345b8b"] ImageLogo:[UIImage imageNamed:@"logo"] title:@"蕪湖亞原子網(wǎng)絡(luò)科技有限公司"] ; //5.將生成的image顯示到imageView上去 self.imageView = [[UIImageView alloc]init] ; self.imageView.frame = CGRectMake(0, 100, 375, 250) ; self.imageView.image = newImage ; [self.view addSubview:self.imageView] ;}   @end