整理一些iOS常用到的代码片段

1:截图(Layer)

- (UIImage *)snapshotImage {
    UIGraphicsBeginImageContextWithOptions(self.bounds.size,
self.opaque, 0);
    CGContextRef context =
UIGraphicsGetCurrentContext();
    [self
renderInContext:context];
    UIImage *image =
UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}
2:截图为PDF格式(Layer)

- (NSData *)snapshotPDF {
    CGRect bounds =
self.bounds;
    NSMutableData* data = [NSMutableData
data];
    CGDataConsumerRef consumer =
CGDataConsumerCreateWithCFData((__bridge
CFMutableDataRef)data);
    CGContextRef context =
CGPDFContextCreate(consumer, &bounds,
NULL);
    CGDataConsumerRelease(consumer);
    if (!context)
return nil;
    CGPDFContextBeginPage(context,
NULL);
    CGContextTranslateCTM(context, 0, bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    [self
renderInContext:context];
    CGPDFContextEndPage(context);
    CGPDFContextClose(context);
    CGContextRelease(context);
    return data;
}
3:获取沙盒路径

- (NSURL *)documentsURL {
    return [[[NSFileManager
defaultManager]
             URLsForDirectory:NSDocumentDirectory
             inDomains:NSUserDomainMask]
lastObject];
}

- (NSString *)documentsPath {
    return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES)
firstObject];
}

4:CPU,内存使用状态

- (int64_t)memoryUsage {
    struct
task_basic_info info;
    mach_msg_type_number_t size =
sizeof(info);
    kern_return_t kern =
task_info(mach_task_self(),
TASK_BASIC_INFO, (task_info_t)&info, &size);
    if (kern !=
KERN_SUCCESS) return -1;
    return info.resident_size;
}

- (float)cpuUsage {
    kern_return_t kr;
    task_info_data_t tinfo;
    mach_msg_type_number_t task_info_count;
    
    task_info_count = TASK_INFO_MAX;
    kr = task_info(mach_task_self(),
TASK_BASIC_INFO, (task_info_t)tinfo, &task_info_count);
    if (kr !=
KERN_SUCCESS) {
        return -1;
    }
    
    thread_array_t thread_list;
    mach_msg_type_number_t thread_count;
    
    thread_info_data_t thinfo;
    mach_msg_type_number_t thread_info_count;
    
    thread_basic_info_t basic_info_th;
    
    kr = task_threads(mach_task_self(), &thread_list, &thread_count);
    if (kr !=
KERN_SUCCESS) {
        return -1;
    }
    
    long tot_sec = 0;
    long tot_usec = 0;
    float tot_cpu = 0;
    int j;
    
    for (j = 0; j < thread_count; j++) {
        thread_info_count = THREAD_INFO_MAX;
        kr = thread_info(thread_list[j],
THREAD_BASIC_INFO,
                         (thread_info_t)thinfo, &thread_info_count);
        if (kr !=
KERN_SUCCESS) {
            return -1;
        }
        
        basic_info_th = (thread_basic_info_t)thinfo;
        
        if (!(basic_info_th->flags &
TH_FLAGS_IDLE)) {
            tot_sec = tot_sec + basic_info_th->user_time.seconds + basic_info_th->system_time.seconds;
            tot_usec = tot_usec + basic_info_th->system_time.microseconds + basic_info_th->system_time.microseconds;
            tot_cpu = tot_cpu + basic_info_th->cpu_usage / (float)TH_USAGE_SCALE;
        }
    }
    
    kr = vm_deallocate(mach_task_self(), (vm_offset_t)thread_list, thread_count *
sizeof(thread_t));
    assert(kr ==
KERN_SUCCESS);
    
    return tot_cpu;
}
5:获取字符串的贝塞尔曲线

+ (UIBezierPath *)bezierPathWithText:(NSString *)text font:(UIFont *)font {
    CTFontRef ctFont = font.CTFontRef;
    if (!ctFont)
return nil;
    NSDictionary *attrs = @{ (__bridge
id)kCTFontAttributeName:(__bridge
id)ctFont };
    NSAttributedString *attrString = [[NSAttributedString
alloc] initWithString:text
attributes:attrs];
    CFRelease(ctFont);
    
    CTLineRef line =
CTLineCreateWithAttributedString((__bridge
CFTypeRef)attrString);
    if (!line)
return nil;
    
    CGMutablePathRef cgPath =
CGPathCreateMutable();
    CFArrayRef runs =
CTLineGetGlyphRuns(line);
    for (CFIndex iRun = 0, iRunMax =
CFArrayGetCount(runs); iRun < iRunMax; iRun++) {
        CTRunRef run = (CTRunRef)CFArrayGetValueAtIndex(runs, iRun);
        CTFontRef runFont =
CFDictionaryGetValue(CTRunGetAttributes(run),
kCTFontAttributeName);
        
        for (CFIndex iGlyph = 0, iGlyphMax =
CTRunGetGlyphCount(run); iGlyph < iGlyphMax; iGlyph++) {
            CFRange glyphRange =
CFRangeMake(iGlyph, 1);
            CGGlyph glyph;
            CGPoint position;
            CTRunGetGlyphs(run, glyphRange, &glyph);
            CTRunGetPositions(run, glyphRange, &position);
            
            CGPathRef glyphPath =
CTFontCreatePathForGlyph(runFont, glyph,
NULL);
            if (glyphPath) {
                CGAffineTransform transform =
CGAffineTransformMakeTranslation(position.x, position.y);
                CGPathAddPath(cgPath, &transform, glyphPath);
                CGPathRelease(glyphPath);
            }
        }
    }
    UIBezierPath *path = [UIBezierPath
bezierPathWithCGPath:cgPath];
    CGRect boundingBox =
CGPathGetPathBoundingBox(cgPath);
    CFRelease(cgPath);
    CFRelease(line);
    
    [path applyTransform:CGAffineTransformMakeScale(1.0, -1.0)];
    [path applyTransform:CGAffineTransformMakeTranslation(0.0, boundingBox.size.height)];
    
    return path;
}
6:根据颜色生成纯色图片

+ (UIImage *)imageWithColor:(UIColor *)color size:(CGSize)size {
    if (!color || size.width <= 0 || size.height <= 0)
return nil;
    CGRect rect =
CGRectMake(0.0f, 0.0f, size.width, size.height);
    UIGraphicsBeginImageContextWithOptions(rect.size,
NO, 0);
    CGContextRef context =
UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, color.CGColor);
    CGContextFillRect(context, rect);
    UIImage *image =
UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}
7:改变图片frame

- (UIImage *)imageByResizeToSize:(CGSize)size contentMode:(UIViewContentMode)contentMode
{
    if (size.width <= 0 || size.height <= 0)
return nil;
    UIGraphicsBeginImageContextWithOptions(size,
NO, self.scale);
    [self
drawInRect:CGRectMake(0, 0, size.width, size.height)
withContentMode:contentMode
clipsToBounds:NO];
    UIImage *image =
UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}
8:利用CPU绘制圆角Image
- (UIImage *)imageByRoundCornerRadius:(CGFloat)radius

                              corners:(UIRectCorner)corners
                          borderWidth:(CGFloat)borderWidth
                          borderColor:(UIColor *)borderColor
                       borderLineJoin:(CGLineJoin)borderLineJoin {
    
    UIGraphicsBeginImageContextWithOptions(self.size,
NO, self.scale);
    CGContextRef context =
UIGraphicsGetCurrentContext();
    CGRect rect =
CGRectMake(0, 0, self.size.width,
self.size.height);
    CGContextScaleCTM(context, 1, -1);
    CGContextTranslateCTM(context, 0, -rect.size.height);
    
    CGFloat minSize =
MIN(self.size.width,
self.size.height);
    if (borderWidth < minSize / 2) {
        UIBezierPath *path = [UIBezierPath
bezierPathWithRoundedRect:CGRectInset(rect, borderWidth, borderWidth)
byRoundingCorners:corners
cornerRadii:CGSizeMake(radius, borderWidth)];
        [path closePath];
        
        CGContextSaveGState(context);
        [path addClip];
        CGContextDrawImage(context, rect,
self.CGImage);
        CGContextRestoreGState(context);
    }
    
    if (borderColor && borderWidth < minSize / 2 && borderWidth > 0) {
        CGFloat strokeInset = (floor(borderWidth *
self.scale) + 0.5) /
self.scale;
        CGRect strokeRect =
CGRectInset(rect, strokeInset, strokeInset);
        CGFloat strokeRadius = radius >
self.scale / 2 ? radius -
self.scale / 2 : 0;
        UIBezierPath *path = [UIBezierPath
bezierPathWithRoundedRect:strokeRect
byRoundingCorners:corners
cornerRadii:CGSizeMake(strokeRadius, borderWidth)];
        [path closePath];
        
        path.lineWidth = borderWidth;
        path.lineJoinStyle = borderLineJoin;
        [borderColor setStroke];
        [path stroke];
    }
    
    UIImage *image =
UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}