由于是随意的知识点，不根据某个方面来写。

1.关于Xcode6模拟器键盘不弹出 -> Command + Shift + K

2.关于调用剪切板复制字符串

+ (void)copyTextWithStr:(NSString *)str {
    UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
    // 复制到剪切板
    pasteboard.string = str;
}

+ (UIColor *)colorWithRGBHex:(UInt32)hex {
	int r = (hex >> 16) & 0xFF;
	int g = (hex >> 8) & 0xFF;
	int b = (hex) & 0xFF;
	
	return [UIColor colorWithRed:r / 255.0f
						   green:g / 255.0f
							blue:b / 255.0f
						   alpha:1.0f];
}

#define DLog(fmt, ...) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__);

#define APPLICATION ([UIApplication sharedApplication])
#define WINDOW ([[UIApplication sharedApplication].windows lastObject])

#define NAV_H 44
#define TOP_Y (iOS_7 ? 64 : NAV_H)
#define TOP_TABLE_VIEW_H ((iOS_7 ? 64 : NAV_H) + NAV_H)

+(UIImage*)CircleImage:(UIImage*)image withParam:(CGFloat)inset withFrame:(CGRect)frame
{
    CGImageRef imageRef = image.CGImage ;
    CGImageRef resultImgRef = CGImageCreateWithImageInRect(imageRef, frame) ;
    UIImage *resultImg = [UIImage imageWithCGImage:resultImgRef scale:image.scale orientation:image.imageOrientation] ;
    CGImageRelease(resultImgRef) ;
    
    UIGraphicsBeginImageContext(resultImg.size);
    
    CGContextRef context = UIGraphicsGetCurrentContext();
//    CGContextSetLineWidth(context, 1);
//    CGContextSetStrokeColorWithColor(context, [UIColor clearColor].CGColor);
    CGRect rect = CGRectMake(inset, inset, resultImg.size.width - inset, resultImg.size.height - inset);
    
    CGContextAddEllipseInRect(context, rect);
    CGContextClip(context);
    
    [resultImg drawInRect:rect];
    
//    CGContextAddEllipseInRect(context, rect);
//    CGContextStrokePath(context);
    UIImage *newimg = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return newimg;
}

8.MD5加密

- (NSString *)MD5 {
    const char *cStr = [self UTF8String];
    unsigned char result[16];
    CC_MD5( cStr, (UInt32)strlen(cStr), result );
    return [NSString stringWithFormat:
            @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
            result[0], result[1], result[2], result[3],
            result[4], result[5], result[6], result[7],
            result[8], result[9], result[10], result[11],
            result[12], result[13], result[14], result[15]
            ];
}

关于iOS小的知识点