3种方法实现UILabel的左上角对齐显示文字

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1、继承UILabel 改变origin的值重新绘制

@interface TopLeftLabel :UILabel

@end

#import"TopLeftLabel.h"

@implementation TopLeftLabel

- (id)initWithFrame:(CGRect)frame {

return [superinitWithFrame:frame];

}

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

CGRect textRect = [supertextRectForBounds:boundslimitedToNumberOfLines:numberOfLines];

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

return textRect;

}

// 重新绘制text的位置

-(void)drawTextInRect:(CGRect)requestedRect {

CGRect actualRect = [selftextRectForBounds:requestedRectlimitedToNumberOfLines:self.numberOfLines];

[superdrawTextInRect:actualRect];

}

@end

2、第二种方法写一个UILabel的分类

@interface UILabel (LeftTopAlign)

- (void) textLeftTopAlign;

@end

@implementation UILabel (LeftTopAlign)

- (void) textLeftTopAlign

{

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStylealloc]init];

paragraphStyle.lineBreakMode =NSLineBreakByWordWrapping;

NSDictionary *attributes = @{NSFontAttributeName:[UIFontsystemFontOfSize:17],NSParagraphStyleAttributeName:paragraphStyle.copy};

CGSize labelSize = [self.textboundingRectWithSize:CGSizeMake(207,999) options:NSStringDrawingUsesLineFragmentOriginattributes:attributes context:nil].size;

CGRect dateFrame =CGRectMake(2,140, CGRectGetWidth(self.frame)-5, labelSize.height);

self.frame = dateFrame;

}

@end

3、直接用UITextView代替 UILabel 然后禁用UITextView 的滚动效果

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