iOS image watermarking and simple encapsulation sample code

Methods to add strings to graph context
- (void)drawAtPoint:(CGPoint)point withAttributes:(nullable NSDictionary<NSAttributedStringKey, id> *)attrs
- (void)drawInRect:(CGRect)rect withAttributes:(nullable NSDictionary<NSAttributedStringKey, id> *)attrs
Methods to add strings to graph context
- (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. To manually create a bitmap context, when creating a bitmap context, you need to specify the size and the specified size determines how big the size of the generated image is.void UIGraphicsBeginImageContext(CGSize size);
 
//2. Draw the content into the context//2.1 Draw the original picture//2.2 Draw text//2.3 Draw the logo 
//3. Generate an image from the context, and combine all the content drawn in the context to generate an image with the same context size as the contextUIImage *newImage = UIGraphicsGetImageFromCurrentImageContext() ;
 
//4. The manually created context must be destroyed manuallyUIGraphicsEndImageContext() ;

#import <UIKit/>
 
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. To manually create a bitmap context UIGraphicsBeginImageContext() ;
  
 //2. Draw into content context //Original image rendering [image drawInRect:CGRectMake(0, 0, , )];
  
 //Word NSDictionary *attributeDict = @{
         NSFontAttributeName : [UIFont systemFontOfSize:],
         NSForegroundColorAttributeName:[UIColor whiteColor],
//         NSBackgroundColorAttributeName :[UIColor redColor]
         } ;
 CGRect rectSize = [string boundingRectWithSize:CGSizeMake(MAXFLOAT, 30) options:NSStringDrawingUsesDeviceMetrics attributes:attributeDict context:nil] ;
 CGFloat x =  -  - 10 ;
 CGFloat y =  - 30 ;
 [string drawAtPoint:CGPointMake(x, y) withAttributes:attributeDict] ;
  
 //Logo Picture CGFloat waterW = 30;
 CGFloat waterH = 30;
 CGFloat waterX = x - waterW - 10 ;
 CGFloat waterY = y - 3 ;
 [imageLogo drawInRect:CGRectMake(waterX, waterY, waterW, waterH)] ;
 
 //3. Generate a new picture from the current context UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext() ;
  
 //4. The manually created context must be destroyed manually UIGraphicsEndImageContext() ;
  
 return newImage ;
}
 
+(UIImage *)WaterImageWithImage:(UIImage *)image ImageLogo:(UIImage *)imageLogo title:(NSString *)string {
 return [[self alloc]WaterImageWithImage:image ImageLogo:imageLogo title:string] ;
}
@end

#import ""
#import ""
@interface ViewController ()
@property(nonatomic,strong)UIImageView *imageView ;
@end
 
@implementation ViewController
 
- (void)viewDidLoad {
 [super viewDidLoad];
  
 //Step on generating a watermarked image: /*
   Images can be generated in any method, not necessarily in the drawRect: method
   1. To manually create a bitmap context, when creating a bitmap context, you need to specify the size and the specified size determines how big the size of the generated image is.
   2. Draw the content into the context
   3. Generate a picture from the context, and combine all the content drawn in the context to generate a picture with the same scale as the context.
   4. The context created manually must be destroyed manually
   */
}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
 UIImage *newImage = [SWWaterMarkImage WaterImageWithImage:[UIImage imageNamed:@"18d8bc3eb13533fa65021ddba5d3fd1f40345b8b"] ImageLogo:[UIImage imageNamed:@"logo"] title:@"Wuhu Asia Atomic Network Technology Co., Ltd."] ;
 //5. Display the generated image on the imageView  = [[UIImageView alloc]init] ;
  = CGRectMake(0, 100, 375, 250) ;
  = newImage ;
 [ addSubview:] ;
}
 
 
 
@end