让 UILabel 垂直方向顶端对齐的代码

UILabel 里放入多行文字，会发现 label 默认居中对齐，很不符合左对齐的传统习惯，下面这段 CocoaChina 版主“angellixf”分享的代码可以让 UILabel 以垂直方向顶端对齐，也就是我们常说的左对齐或右对齐

//

// VerticallyAlignedLabel.h

//
#import
typedef enum VerticalAlignment {

VerticalAlignmentTop,

VerticalAlignmentMiddle,

VerticalAlignmentBottom,

} VerticalAlignment;
@interface VerticallyAlignedLabel : UILabel {

@private

VerticalAlignment verticalAlignment_;

}
@property (nonatomic, assign) VerticalAlignment verticalAlignment;
@end
//

// VerticallyAlignedLabel.m

//
#import "VerticallyAlignedLabel.h"
@implementation VerticallyAlignedLabel
@synthesize verticalAlignment = verticalAlignment_;
- (id)initWithFrame:(CGRect)frame {

if (self = [super initWithFrame:frame]) {

self.verticalAlignment = VerticalAlignmentMiddle;

}

return self;

}
- (void)setVerticalAlignment:(VerticalAlignment)verticalAlignment {

verticalAlignment_ = verticalAlignment;

[self setNeedsDisplay];

}
- (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines {

CGRect textRect = [super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines];

switch (self.verticalAlignment) {

case VerticalAlignmentTop:

textRect.origin.y = bounds.origin.y;

break;

case VerticalAlignmentBottom:

textRect.origin.y = bounds.origin.y + bounds.size.height - textRect.size.height;

break;

case VerticalAlignmentMiddle:

// Fall through.

default:

textRect.origin.y = bounds.origin.y + (bounds.size.height - textRect.size.height) / 2.0;

}

return textRect;

}
-(void)drawTextInRect:(CGRect)requestedRect {

CGRect actualRect = [self textRectForBounds:requestedRect limitedToNumberOfLines:self.numberOfLines];

[super drawTextInRect:actualRect];

}
@end