UIColor的封装

#import <UIKit/UIKit.h>

 

@interface UIColor (Hex)

 

// 默认alpha位1

+ (UIColor *)colorWithHexString:(NSString *)color;

 

//从十六进制字符串获取颜色，

//color:支持@“#123456”、 @“0X123456”、 @“123456”三种格式

+ (UIColor *)colorWithHexString:(NSString *)color alpha:(CGFloat)alpha;

 

@end

 

--------------------.m----------------

 

#import "UIColor+Hex.h"

 

@implementation UIColor (Hex)

 

+ (UIColor *)colorWithHexString:(NSString *)color alpha:(CGFloat)alpha

{

    //删除字符串中的空格

    NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

    // String should be 6 or 8 characters

    if ([cString length] < 6)

    {

        return [UIColor clearColor];

    }

    // strip 0X if it appears

    //如果是0x开头的，那么截取字符串，字符串从索引为2的位置开始，一直到末尾

    if ([cString hasPrefix:@"0X"])

    {

        cString = [cString substringFromIndex:2];

    }

    //如果是#开头的，那么截取字符串，字符串从索引为1的位置开始，一直到末尾

    if ([cString hasPrefix:@"#"])

    {

        cString = [cString substringFromIndex:1];

    }

    if ([cString length] != 6)

    {

        return [UIColor clearColor];

    }

    

    // Separate into r, g, b substrings

    NSRange range;

    range.location = 0;

    range.length = 2;

    //r

    NSString *rString = [cString substringWithRange:range];

    //g

    range.location = 2;

    NSString *gString = [cString substringWithRange:range];

    //b

    range.location = 4;

    NSString *bString = [cString substringWithRange:range];

    

    // Scan values

    unsigned int r, g, b;

    [[NSScanner scannerWithString:rString] scanHexInt:&r];

    [[NSScanner scannerWithString:gString] scanHexInt:&g];

    [[NSScanner scannerWithString:bString] scanHexInt:&b];

    return [UIColor colorWithRed:((float)r / 255.0f) green:((float)g / 255.0f) blue:((float)b / 255.0f) alpha:alpha];

}

 

//默认alpha值为1

+ (UIColor *)colorWithHexString:(NSString *)color

{

    return [self colorWithHexString:color alpha:1.0f];

}

 

@end