记录iOS平时使用的技巧

取图片某一像素点的颜色 在UIImage的分类中

  - (UIColor *)colorAtPixel:(CGPoint)point
{
    if (!CGRectContainsPoint(CGRectMake(0.0f, 0.0f, self.size.width, self.size.height), point))
    {
        return nil;
    }
    
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    int bytesPerPixel = 4;
    int bytesPerRow = bytesPerPixel * 1;
    NSUInteger bitsPerComponent = 8;
    unsigned char pixelData[4] = {0, 0, 0, 0};
    
    CGContextRef context = CGBitmapContextCreate(pixelData,
                                                 1,
                                                 1,
                                                 bitsPerComponent,
                                                 bytesPerRow,
                                                 colorSpace,
                                                 kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    CGColorSpaceRelease(colorSpace);
    CGContextSetBlendMode(context, kCGBlendModeCopy);
    
    CGContextTranslateCTM(context, -point.x, point.y - self.size.height);
    CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, self.size.width, self.size.height), self.CGImage);
    CGContextRelease(context);
    
    CGFloat red   = (CGFloat)pixelData[0] / 255.0f;
    CGFloat green = (CGFloat)pixelData[1] / 255.0f;
    CGFloat blue  = (CGFloat)pixelData[2] / 255.0f;
    CGFloat alpha = (CGFloat)pixelData[3] / 255.0f;
    
    return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
}

iOS 获取汉字的拼音

+ (NSString *)transform:(NSString *)chinese
{    
    //将NSString装换成NSMutableString 
    NSMutableString *pinyin = [chinese mutableCopy];    
    //将汉字转换为拼音(带音标)    
    CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformMandarinLatin, NO);    
    NSLog(@"%@", pinyin);    
    //去掉拼音的音标    
    CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformStripCombiningMarks, NO);    
    NSLog(@"%@", pinyin);    
    //返回最近结果    
    return pinyin;
 }

判断view是不是指定视图的子视图

BOOL isView = [textView isDescendantOfView:self.view];

NSArray 快速求总和 最大值 最小值 和 平均值

NSArray *array = [NSArray arrayWithObjects:@"2.0", @"2.3", @"3.0", @"4.0", @"10", nil];
CGFloat sum = [[array valueForKeyPath:@"@sum.floatValue"] floatValue];
CGFloat avg = [[array valueForKeyPath:@"@avg.floatValue"] floatValue];
CGFloat max =[[array valueForKeyPath:@"@max.floatValue"] floatValue];
CGFloat min =[[array valueForKeyPath:@"@min.floatValue"] floatValue];
NSLog(@"%f\n%f\n%f\n%f",sum,avg,max,min);

图片上绘制文字 写一个UIImage的category

- (UIImage *)imageWithTitle:(NSString *)title fontSize:(CGFloat)fontSize
{
    //画布大小
    CGSize size=CGSizeMake(self.size.width,self.size.height);
    //创建一个基于位图的上下文
    UIGraphicsBeginImageContextWithOptions(size,NO,0.0);//opaque:NO  scale:0.0
    
    [self drawAtPoint:CGPointMake(0.0,0.0)];
    
    //文字居中显示在画布上
    NSMutableParagraphStyle* paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
    paragraphStyle.lineBreakMode = NSLineBreakByCharWrapping;
    paragraphStyle.alignment=NSTextAlignmentCenter;//文字居中
    
    //计算文字所占的size,文字居中显示在画布上
    CGSize sizeText=[title boundingRectWithSize:self.size options:NSStringDrawingUsesLineFragmentOrigin
                                     attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]}context:nil].size;
    CGFloat width = self.size.width;
    CGFloat height = self.size.height;
    
    CGRect rect = CGRectMake((width-sizeText.width)/2, (height-sizeText.height)/2, sizeText.width, sizeText.height);
    //绘制文字
    [title drawInRect:rect withAttributes:@{ NSFontAttributeName:[UIFont systemFontOfSize:fontSize],NSForegroundColorAttributeName:[ UIColor whiteColor],NSParagraphStyleAttributeName:paragraphStyle}];
    
    //返回绘制的新图形
    UIImage *newImage= UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

字符长度，一个汉字算两个字符

//方法一：
- (int)convertToInt:(NSString*)strtemp
{
    int strlength = 0;
    char* p = (char*)[strtemp cStringUsingEncoding:NSUnicodeStringEncoding];
    for (int i=0 ; i<[strtemp lengthOfBytesUsingEncoding:NSUnicodeStringEncoding] ;i++)
    {
        if (*p)
        {
            p++;
            strlength++;
        }
        else
        {
            p++;
        }
        
    }
    return strlength;
}

//方法二：
-(NSUInteger) unicodeLengthOfString: (NSString *) text
{
    NSUInteger asciiLength = 0;
    for (NSUInteger i = 0; i < text.length; i++)
    {
        unichar uc = [text characterAtIndex: i];
        asciiLength += isascii(uc) ? 1 : 2;
    }
    return asciiLength;
}

字符串中是否含有中文

+ (BOOL)checkIsChinese:(NSString *)string
{
    for (int i=0; i<string.length; i++)
    {
        unichar ch = [string characterAtIndex:i];
        if (0x4E00 <= ch  && ch <= 0x9FA5)
        {
            return YES;
        }
    }
    return NO;
}

汉字转拼音

    NSString *chineseText = @"啦啦啦德玛西亚";
    if (chineseText.length > 0)
    {
        NSMutableString *ms = [[NSMutableString alloc] initWithString:chineseText];
        
        //带声标
        if (CFStringTransform((__bridge CFMutableStringRef)ms, 0, kCFStringTransformMandarinLatin, NO))
        {
            NSLog(@"pinyin: %@", ms);
        }
        
        //不带声标
        if (CFStringTransform((__bridge CFMutableStringRef)ms, 0, kCFStringTransformStripDiacritics, NO))
        {
            NSLog(@"pinyin: %@", ms);
        }
        
        NSString *name = [NSString stringWithString:ms];
        NSLog(@"%@",name);
    }

简单的获取当前时间

// CFAbsoluteTime其实就是double
CFAbsoluteTime time = CFAbsoluteTimeGetCurrent();

让一个视图始终在最前面

view.layer.zPosition = 999;

利用宏在扩展类添加属性

#define ASSOCIATED(propertyName, setter, type, objc_AssociationPolicy)\
- (type)propertyName {\
return objc_getAssociatedObject(self, _cmd);\
}\
\
- (void)setter:(type)object\
{\
objc_setAssociatedObject(self, @selector(propertyName), object, objc_AssociationPolicy);\
}

已某个view截屏并生成Image

- (UIImage*)viewShot{
    UIGraphicsBeginImageContext(self.bounds.size);
    [self.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}