iOS常用小功能（获得屏幕图像、压缩图片、加边框、调整label的size）

1获得屏幕图像

-(UIImage *)imageFromView:(UIView *) theView{

UIGraphicsBeginImageContext(theView.frame.size);

CGContextRef context = UIGraphicsGetCurrentContext();

[theView.layer renderInContext:context];

UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return theImage;

}

2、label 的动态size

-(CGSize)labelAutoCalculateRectWith:(NSString*)text FontSize:(CGFloat)fontSize MaxSize:(CGSize)maxSize{

NSMutableParagraphStyle* paragraphStyle = [[NSMutableParagraphStyle alloc]init];

paragraphStyle.lineBreakMode=NSLineBreakByWordWrapping;

NSDictionary* attributes =@{NSFontAttributeName:[UIFont fontWithName:@"MicrosoftYaHei" size:fontSize],NSParagraphStyleAttributeName:paragraphStyle.copy};

CGSize labelSize = [text boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading|NSStringDrawingTruncatesLastVisibleLine attributes:attributes context:nil].size;

labelSize.height=ceil(labelSize.height);

return labelSize;

}

3、时间戳转化为时间

-(NSString*)TimeTrasformWithDate:(NSString *)dateString{

NSDateFormatter *formatter = [[NSDateFormatter alloc]init];

[formatter setDateFormat:@"YY-MM-dd HH:mm"];

[formatter setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Beijing"]];

NSString *date = [formatter stringFromDate:[NSDate dateWithTimeIntervalSince1970:dateString.integerValue]];

//NSLog(@"date1:%@",date);

return date;

}

4、RGB转化为颜色

+ (UIColor *)colorFromHexRGB:(NSString *)inColorString{

UIColor *result = nil;

unsignedint colorCode = 0;

unsignedchar redByte, greenByte, blueByte;

if (nil != inColorString) {

NSScanner *scanner = [NSScanner scannerWithString:inColorString];

(void) [scanner scanHexInt:&colorCode]; // ignore error

}

redByte = (unsignedchar) (colorCode >> 16);

greenByte = (unsignedchar) (colorCode >> 8);

blueByte = (unsignedchar) (colorCode);// masks off high bits

result = [UIColor colorWithRed:(float)redByte / 0xff green:(float)greenByte/0xff blue:(float)blueByte / 0xff alpha:1.0];

return result;

}

5、加边框

UIRectCorner corners=UIRectCornerTopLeft | UIRectCornerTopRight;

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:corners cornerRadii:CGSizeMake(4,0)];

CAShapeLayer *maskLayer = [CAShapeLayer layer];

maskLayer.frame = view.bounds;

maskLayer.path = maskPath.CGPath;

view.layer.mask = maskLayer;

6、压缩图片

+ (UIImage*)imageWithImageSimple:(UIImage*)image scaledToSize:(CGSize)newSize{ 

//创建一个图形上下文形象

UIGraphicsBeginImageContext(newSize);// 告诉旧图片画在这个新的环境,所需的// new size

[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];//获取上下文的新形象

UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext(); // 结束上下文

UIGraphicsEndImageContext();

return newImage;

}

7、textfield的placeho

[textFsetValue:[UIColor whiteColor] forKeyPath:@"_placeholderLabel.textColor"];

[textFsetValue:[UIFont boldSystemFontOfSize:15]forKeyPath:@"_placeholderLabel.font"];

8、调用此方法改变label最后2个字符的大小

- (void)label:(UILabel *)label BehindTextSize:(NSInteger)integer{

NSMutableAttributedString *mutaString = [[NSMutableAttributedString alloc] initWithString:label.text]; [mutaString addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:16] range:NSMakeRange(label.text.length-2,2)];

label.attributedText = mutaString;

}

10、图片灰度

-(UIImage*) grayscaleImage: (UIImage *)image{

CGSizesize =image.size;

CGRect rect = CGRectMake(0.0f,0.0f,image.size.width,image.size.height);// Create a mono/gray color space CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

CGContextRef context = CGBitmapContextCreate(nil, size.width,size.height,8,0, colorSpace, kCGImageAlphaNone);

CGColorSpaceRelease(colorSpace);// Draw the image into the grayscale context

CGContextDrawImage(context, rect, [image CGImage]);

CGImageRef grayscale = CGBitmapContextCreateImage(context);

CGContextRelease(context);// Recover the image

UIImage*img = [UIImage imageWithCGImage:grayscale];

CFRelease(grayscale);

return img;

}