iOS-生成简单的渐变图片

.h

typedef NS_ENUM(NSUInteger, GradientType) {

GradientTypeTopToBottom = 0,//从上到下
GradientTypeLeftToRight = 1,//从左到右
GradientTypeUpleftToLowright = 2,//左上到右下
GradientTypeUprightToLowleft = 3,//右上到左下

};

@interface UIImage (EXtension)

• (UIImage *)imageWithColor:(UIColor *)color;

/** 设置图片的渐变色(颜色->图片)

@param colors 渐变颜色数组 @param gradientType 渐变样式 @param imgSize 图片大小 @return 颜色->图片
*/

• (UIImage )gradientColorImageFromColors:(NSArray)colors gradientType:(GradientType)gradientType imgSize:(CGSize)imgSize;

@end

.m

import "UIImage+EXtension.h"

@implementation UIImage (EXtension)

//这个方法可以抽取到 UIImage 的分类中

• (UIImage *)imageWithColor:(UIColor *)color
  {
  NSParameterAssert(color != nil);

  CGRect rect = CGRectMake(0, 0, 1, 1);
  // Create a 1 by 1 pixel context
  UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
  [color setFill];
  UIRectFill(rect); // Fill it with your color
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();

  return image;
  }

• (UIImage )gradientColorImageFromColors:(NSArray)colors gradientType:(GradientType)gradientType imgSize:(CGSize)imgSize {
  NSMutableArray *ar = [NSMutableArray array];
  for(UIColor *c in colors) {
  [ar addObject:(id)c.CGColor];
  }
  UIGraphicsBeginImageContextWithOptions(imgSize, YES, 1);
  CGContextRef context = UIGraphicsGetCurrentContext();
  CGContextSaveGState(context);
  CGColorSpaceRef colorSpace = CGColorGetColorSpace([[colors lastObject] CGColor]);
  CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (CFArrayRef)ar, NULL);
  CGPoint start;
  CGPoint end;
  switch (gradientType) {
  case GradientTypeTopToBottom:
  start = CGPointMake(0.0, 0.0);
  end = CGPointMake(0.0, imgSize.height);
  break;
  case GradientTypeLeftToRight:
  start = CGPointMake(0.0, 0.0);
  end = CGPointMake(imgSize.width, 0.0);
  break;
  case GradientTypeUpleftToLowright:
  start = CGPointMake(0.0, 0.0);
  end = CGPointMake(imgSize.width, imgSize.height);
  break;
  case GradientTypeUprightToLowleft:
  start = CGPointMake(imgSize.width, 0.0);
  end = CGPointMake(0.0, imgSize.height);
  break;
  default:
  break;
  }
  CGContextDrawLinearGradient(context, gradient, start, end,kCGGradientDrawsBeforeStartLocation | kCGGradientDrawsAfterEndLocation);
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  CGGradientRelease(gradient);
  CGContextRestoreGState(context);
  CGColorSpaceRelease(colorSpace);
  UIGraphicsEndImageContext();
  return image;
  }

@end

屏幕快照 2019-10-21 下午5.54.41.png