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