不多说，上代码

.h文件

#import <UIKit/UIKit.h>

typedef NS_ENUM(NSInteger, JWCropImageStyle){
    JWCropImageStyleRight               =0,      // 右半部分
    JWCropImageStyleCenter              =1,      // 中间部分
    JWCropImageStyleLeft                =2,      // 左半部分
    JWCropImageStyleRightOneOfThird     =3,      // 右侧三分之一部分
    JWCropImageStyleCenterOneOfThird    =4,      // 中间三分之一部分
    JWCropImageStyleLeftOneOfThird      =5,      // 左侧三分之一部分
    JWCropImageStyleRightQuarter        =6,      // 右侧四分之一部分
    JWCropImageStyleCenterRightQuarter  =7,      // 中间右侧四分之一部分
    JWCropImageStyleCenterLeftQuarter   =8,      // 中间左侧四分之一部分
    JWCropImageStyleLeftQuarter         =9,      // 左侧四分之一部分
    JWIDCardImageStyleCenter              =10,    // id card
};

@interface UIImage (Extension)

//@interface UIImage (Crop)
- (UIImage *)imageByCroppingWithStyle:(JWCropImageStyle)style;

@end

.m文件

#import "UIImage+crop.h"

@implementation UIImage (Extension)

- (UIImage *)imageByCroppingWithStyle:(JWCropImageStyle)style
{
    CGRect rect;
    switch (style) {
        case JWCropImageStyleLeft:
            rect = CGRectMake(0, 0, self.size.width/2, self.size.height);
            break;
        case JWCropImageStyleCenter:
            rect = CGRectMake(0, self.size.height/4, self.size.width, self.size.height/2);
            break;
        case JWCropImageStyleRight:
            rect = CGRectMake(self.size.width/2, 0, self.size.width/2, self.size.height);
            break;
        case JWCropImageStyleLeftOneOfThird:
            rect = CGRectMake(0, 0, self.size.width/3, self.size.height);
            break;
        case JWCropImageStyleCenterOneOfThird:
            rect = CGRectMake(self.size.width/3, 0, self.size.width/3, self.size.height);
            break;
        case JWCropImageStyleRightOneOfThird:
            rect = CGRectMake(self.size.width/3*2, 0, self.size.width/3, self.size.height);
            break;
        case JWCropImageStyleLeftQuarter:
            rect = CGRectMake(0, 0, self.size.width/4, self.size.height);
            break;
        case JWCropImageStyleCenterLeftQuarter:
            rect = CGRectMake(self.size.width/4, 0, self.size.width/4, self.size.height);
            break;
        case JWCropImageStyleCenterRightQuarter:
            rect = CGRectMake(self.size.width/4*2, 0, self.size.width/4, self.size.height);
            break;
        case JWCropImageStyleRightQuarter:
            rect = CGRectMake(self.size.width/4*3, 0, self.size.width/4, self.size.height);
            break;
        case JWIDCardImageStyleCenter:
//            rect = CGRectMake(0, self.size.height/4, self.size.width, self.size.height/2);
            rect = CGRectMake(self.size.width/4+100, 200, self.size.width/2, self.size.height);
            break;
        default:
            break;
    }
    CGImageRef imageRef = self.CGImage;
    CGImageRef imagePartRef = CGImageCreateWithImageInRect(imageRef, rect);
    UIImage *cropImage = [UIImage imageWithCGImage:imagePartRef];
    CGImageRelease(imagePartRef);
    return cropImage;
}

@end

这个是之前在网上找的，忘了是谁写的，如果谁知道，麻烦告诉我一下原作者的链接