通过颜色生成图片

/**
 *  通过颜色生成纯颜色的图片
 */

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

#import "AppDelegate.h"
#import "RootViewController.h"
@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];

    self.window.rootViewController = [[RootViewController alloc] init];

    [self.window makeKeyAndVisible];
    return YES;
}

@end

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController

@end

#import "RootViewController.h"
#import "UIImage+CreatImageWithColor.h"

@interface RootViewController ()

@end

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];

//    UIImage *image = [UIImage imageWithColor:[UIColor redColor] imageWidth:100 imageWithHeight:100];
    UIImage *image = [UIImage imageWithColor:[UIColor yellowColor]];
    UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
    imageView.frame = CGRectMake(100, 100, 200, 200);
    [self.view addSubview:imageView];
}

@end

#import <UIKit/UIKit.h>

@interface UIImage (CreatImageWithColor)

/**
 *  通过颜色生成该纯颜色的图片
 *
 *  @param color 生成图片的颜色
 *
 *  @return 返回图片
 */
+ (UIImage *)imageWithColor:(UIColor *)color;

/**
 *  通过颜色生成该纯颜色的图片
 *
 *  @param color  生成图片的颜色
 *  @param width  生成图片的宽
 *  @param height 生成图片的高
 *
 *  @return 返回图片
 */
+ (UIImage *)imageWithColor:(UIColor *)color imageWidth:(CGFloat)width imageWithHeight:(CGFloat)height;

@end

#import "UIImage+CreatImageWithColor.h"

@implementation UIImage (CreatImageWithColor)

+ (UIImage *)imageWithColor:(UIColor *)color{
    return [UIImage imageWithColor:color imageWidth:100 imageWithHeight:100];
}

+ (UIImage *)imageWithColor:(UIColor *)color imageWidth:(CGFloat)width imageWithHeight:(CGFloat)height{

    //开启基于位图的图形上下文
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(width,height), NO, 0.0);
    // 设置画笔的颜色
    [color set];
    // 画矩形，并填充
    UIRectFill(CGRectMake(0, 0, width, height));
    //获取图片
    UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
    //关闭上下文
    UIGraphicsEndImageContext();

    return resultImage;
}

@end