為了防止工程師泄露用戶信息茵典，我們有個(gè)需求是在列表上面添加水印系冗。我封裝了這個(gè)視圖分享出來(lái)祝钢。

水印效果圖.png

watermarkView.h

#import <UIKit/UIKit.h>

@interface watermarkView : UIImageView

/**
 設(shè)置水印

 @param frame 水印大小
 @param markText 水印顯示的文字
 */
- (instancetype)initWithFrame:(CGRect)frame WithText:(NSString *)markText;

@end

watermarkView.m

#import "watermarkView.h"

#define HORIZONTAL_SPACE 30//水平間距
#define VERTICAL_SPACE 50//豎直間距
#define CG_TRANSFORM_ROTATION (M_PI_2 / 3)//旋轉(zhuǎn)角度(正旋45度 || 反旋45度)

@implementation watermarkView

- (instancetype)initWithFrame:(CGRect)frame WithText:(NSString *)markText{
    if(self = [super initWithFrame:frame]){
        
        UIFont *font = [UIFont systemFontOfSize:14];
        
        UIColor *color = YTHColorAlpha(152, 152, 152, 0.1);
        
        //原始image的寬高
        CGFloat viewWidth = frame.size.width;
        CGFloat viewHeight = frame.size.height;
        
        //為了防止圖片失真窖杀，繪制區(qū)域?qū)捀吆驮紙D片寬高一樣
        UIGraphicsBeginImageContext(CGSizeMake(viewWidth, viewHeight));
        
        //sqrtLength：原始image的對(duì)角線length角骤。在水印旋轉(zhuǎn)矩陣中只要矩陣的寬高是原始image的對(duì)角線長(zhǎng)度投蝉，無(wú)論旋轉(zhuǎn)多少度都不會(huì)有空白养葵。
        CGFloat sqrtLength = sqrt(viewWidth*viewWidth + viewHeight*viewHeight);
        //文字的屬性
        NSDictionary *attr = @{
                               //設(shè)置字體大小
                               NSFontAttributeName: font,
                               //設(shè)置文字顏色
                               NSForegroundColorAttributeName :color,
                               };
        NSString* mark = markText;
        NSMutableAttributedString *attrStr = [[NSMutableAttributedString alloc] initWithString:mark attributes:attr];
        //繪制文字的寬高
        CGFloat strWidth = attrStr.size.width;
        CGFloat strHeight = attrStr.size.height;
        
        //開(kāi)始旋轉(zhuǎn)上下文矩陣，繪制水印文字
        CGContextRef context = UIGraphicsGetCurrentContext();
        
        //將繪制原點(diǎn)（0瘩缆，0）調(diào)整到原image的中心
        CGContextConcatCTM(context, CGAffineTransformMakeTranslation(viewWidth/2, viewHeight/2));
        //以繪制原點(diǎn)為中心旋轉(zhuǎn)
        CGContextConcatCTM(context, CGAffineTransformMakeRotation(CG_TRANSFORM_ROTATION));
        //將繪制原點(diǎn)恢復(fù)初始值关拒，保證當(dāng)前context中心和源image的中心處在一個(gè)點(diǎn)(當(dāng)前context已經(jīng)旋轉(zhuǎn)，所以繪制出的任何layer都是傾斜的)
        CGContextConcatCTM(context, CGAffineTransformMakeTranslation(-viewWidth/2, -viewHeight/2));
        
        //計(jì)算需要繪制的列數(shù)和行數(shù)
        int horCount = sqrtLength / (strWidth + HORIZONTAL_SPACE) + 1;
        int verCount = sqrtLength / (strHeight + VERTICAL_SPACE) + 1;
        
        //此處計(jì)算出需要繪制水印文字的起始點(diǎn)，由于水印區(qū)域要大于圖片區(qū)域所以起點(diǎn)在原有基礎(chǔ)上移
        CGFloat orignX = -(sqrtLength-viewWidth)/2;
        CGFloat orignY = -(sqrtLength-viewHeight)/2;
        
        //在每列繪制時(shí)X坐標(biāo)疊加
        CGFloat tempOrignX = orignX;
        //在每行繪制時(shí)Y坐標(biāo)疊加
        CGFloat tempOrignY = orignY;
        for (int i = 0; i < horCount * verCount; i++) {
            [mark drawInRect:CGRectMake(tempOrignX, tempOrignY, strWidth, strHeight) withAttributes:attr];
            if (i % horCount == 0 && i != 0) {
                tempOrignX = orignX;
                tempOrignY += (strHeight + VERTICAL_SPACE);
            }else{
                tempOrignX += (strWidth + HORIZONTAL_SPACE);
            }
        }
        //根據(jù)上下文制作成圖片
                UIImage *finalImg = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        CGContextRestoreGState(context);
        
        self.image = finalImg;
    }
    
    return self;
}

-(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
    
    //1.判斷自己能否接收事件
    if(self.userInteractionEnabled == NO || self.hidden == YES || self.alpha <= 0.01) {
        return nil;
    }
    //2.判斷當(dāng)前點(diǎn)在不在當(dāng)前View.
    if (![self pointInside:point withEvent:event]) {
        return nil;
    }
    //3.從后往前遍歷自己的子控件.讓子控件重復(fù)前兩步操作,(把事件傳遞給,讓子控件調(diào)用hitTest)
    int count = (int)self.subviews.count;
    for (int i = count - 1; i >= 0; i--) {
        //取出每一個(gè)子控件
        UIView *chileV =  self.subviews[I];
        //把當(dāng)前的點(diǎn)轉(zhuǎn)換成子控件坐標(biāo)系上的點(diǎn).
        CGPoint childP = [self convertPoint:point toView:chileV];
        UIView *fitView = [chileV hitTest:childP withEvent:event];
        //判斷有沒(méi)有找到最適合的View
        if(fitView){
            return fitView;
        }
    }
    
    //4.沒(méi)有找到比它自己更適合的View.那么它自己就是最適合的View
    return self;
}

//作用:判斷當(dāng)前點(diǎn)在不在它調(diào)用View,(誰(shuí)調(diào)用pointInside,這個(gè)View就是誰(shuí))
//什么時(shí)候調(diào)用:它是在hitTest方法當(dāng)中調(diào)用的.
//注意:point點(diǎn)必須得要跟它方法調(diào)用者在同一個(gè)坐標(biāo)系里面
-(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event{
    NSLog(@"%s",__func__);
    return NO;
}

使用方法

   //加水印
    watermarkView *watermark = [[watermarkView alloc] initWithFrame:CGRectMake(0, 0, KScreenW, KScreenH) WithText:@"測(cè)試"];
    [self.view addSubview:watermark];