iOS实现渐变颜色

下面是我的两种实现:

1.直接图片展示,注意图片的变形问题;

2.用CAGradientLayer渐变颜色实现;

代码如下:

//
//  ViewController.m
//  ImageStrenchDemo
//
//  Created by 思 彭 on 17/3/14.
//  Copyright © 2017年 思 彭. All rights reserved.
//

#import "ViewController.h"

// rgb颜色转换（16进制->10进制）
#define UIColorFromRGB(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 green:((float)((rgbValue & 0xFF00) >> 8))/255.0 blue:((float)(rgbValue & 0xFF))/255.0 alpha:1.0]

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UIImageView *headImgViewBg = [[UIImageView alloc] initWithFrame:self.view.bounds];
    [headImgViewBg setImage:[UIImage imageNamed:@"bj"]];
    [self.view addSubview:headImgViewBg];
    [self setupUI];
    [self setupImage];

}

// 图片实现渐变
- (void)setupImage {

    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = CGRectMake(, , , );
    UIImage *image1 = [UIImage imageNamed:@""];
    UIImage *resizeImage = [image1 resizableImageWithCapInsets:UIEdgeInsetsMake(image1.size.height*0.5, image1.size.width*0.3, image1.size.height*0.5, image1.size.width*0.5)resizingMode:UIImageResizingModeStretch];
    [button setBackgroundImage:resizeImage forState:UIControlStateNormal ];
    [button setTitle:@"dcevbvhvjrvrjvn" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
    [self.view addSubview:button];
}

// 颜色值实现渐变
- (void)setupUI {

    UIView *bgView = [[UIView alloc]initWithFrame:CGRectMake(, , , )];
    UIImageView *headImgViewBg = [[UIImageView alloc] initWithFrame:CGRectMake(, , , )];
    bgView.layer.masksToBounds = YES;
    bgView.layer.cornerRadius = ;
    [bgView addSubview:headImgViewBg];
    [self.view addSubview:bgView];
    CAGradientLayer *gradient = [CAGradientLayer layer];
    gradient.frame = headImgViewBg.frame;
    gradient.colors = [NSArray arrayWithObjects:(id)UIColorFromRGB(0x752ccd).CGColor,
                       (id)UIColorFromRGB(0xcd1f87).CGColor,nil];
    gradient.startPoint = CGPointMake(, 0.5);
    gradient.endPoint = CGPointMake(, 0.5);
    [headImgViewBg.layer insertSublayer:gradient atIndex:];
}

@end