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

摘要：获得屏幕图像,label的动态size,时间戳转化为时间,RGB转化成颜色,加边框,压缩图片,textfield的placeholder,图片做灰度处理

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转化成颜色

+ (UIColor *)colorFromHexRGB:(NSString *)inColorString
{
UIColor *result = nil;
unsigned int colorCode = 0;
unsigned char redByte, greenByte, blueByte;

if (nil != inColorString)
{
NSScanner *scanner = [NSScanner scannerWithString:inColorString];
(void) [scanner scanHexInt:&colorCode]; // ignore error
}
redByte = (unsigned char) (colorCode >> 16);
greenByte = (unsigned char) (colorCode >> 8);
blueByte = (unsigned char) (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placeholder

[textF setValue:[UIColor whiteColor] forKeyPath:@"_placeholderLabel.textColor"];
[textF setValue:[UIFont boldSystemFontOfSize:15] forKeyPath:@"_placeholderLabel.font"];

8.布局

butLeft. imageEdgeInsets = UIEdgeInsetsMake (7 , 5 , 7 , 25  );
butLeft.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;

9.//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.

- (void)ChangeLabelTextColor:(UILabel *)label

{
NSMutableAttributedString *mutaString = [[NSMutableAttributedString alloc] initWithString:label.text];

[mutaString addAttribute:NSForegroundColorAttributeName value:[UIColor colorWithRed:207/255.0 green:34/255.0 blue:42/255.0 alpha:1] range:NSMakeRange(0, 5)];
label.attributedText = mutaString;
}

if ([tableView respondsToSelector:@selector(setSeparatorInset:)]) {

[tableView setSeparatorInset:UIEdgeInsetsZero];

}
if ([[UIDevice currentDevice].systemVersion floatValue] >= 8.0) {
if ([tableView respondsToSelector:@selector(setLayoutMargins:)]) {

[tableView setLayoutMargins:UIEdgeInsetsZero];

}
}

// Do any additional setup after loading the view.
}
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath

{

if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {

[cell setSeparatorInset:UIEdgeInsetsZero];

}
if ([[UIDevice currentDevice].systemVersion floatValue] >= 8.0) {
if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {

[cell setLayoutMargins:UIEdgeInsetsZero];

}
}
}

11.图片变灰度

-(UIImage *) grayscaleImage: (UIImage *) image
{
CGSize size = 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;
}

13.16进制转rgb

#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]