UIColor的分类：
.h文件:
#import <UIKit/UIKit.h>
@interface UIColor (HexColor)
+ (UIColor *)colorWithHexString:(NSString *)color alpha:(CGFloat)alpha;//HexString转RGB
@end
.m文件:
#import "UIColor+HexColor.h"
@implementation UIColor (HexColor)
+ (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];
}
@end
