iOS UILabel

这里我们继续介绍下UILabel

首先我们看看UILabel.h文件，给我们提供了什么东西？

//
//  UILabel.h
//  UIKit
//
//  Copyright (c) 2006-2013, Apple Inc. All rights reserved.
//
#import <Foundation/Foundation.h>
#import <CoreGraphics/CoreGraphics.h>
#import <UIKit/UIView.h>
#import <UIKit/UIStringDrawing.h>
#import <UIKit/UIKitDefines.h>
@class UIColor, UIFont;
NS_CLASS_AVAILABLE_IOS(2_0) @interface UILabel : UIView <NSCoding>
@property(nonatomic,copy)   NSString           *text;            // default is nil
@property(nonatomic,retain) UIFont             *font;            // default is nil (system font 17 plain)
@property(nonatomic,retain) UIColor            *textColor;       // default is nil (text draws black)
@property(nonatomic,retain) UIColor            *shadowColor;     // default is nil (no shadow)
@property(nonatomic)        CGSize             shadowOffset;    // default is CGSizeMake(0, -1) -- a top shadow
@property(nonatomic)        NSTextAlignment    textAlignment;   // default is NSTextAlignmentLeft
@property(nonatomic)        NSLineBreakMode    lineBreakMode;   // default is NSLineBreakByTruncatingTail. used for single and multiple lines of text
// the underlying attributed string drawn by the label, if set, the label ignores the properties above.
@property(nonatomic,copy)   NSAttributedString *attributedText NS_AVAILABLE_IOS(6_0);  // default is nil
// the 'highlight' property is used by subclasses for such things as pressed states. it's useful to make it part of the base class as a user property
@property(nonatomic,retain)               UIColor *highlightedTextColor; // default is nil
@property(nonatomic,getter=isHighlighted) BOOL     highlighted;          // default is NO
@property(nonatomic,getter=isUserInteractionEnabled) BOOL userInteractionEnabled;  // default is NO
@property(nonatomic,getter=isEnabled)                BOOL enabled;                 // default is YES. changes how the label is drawn
// this determines the number of lines to draw and what to do when sizeToFit is called. default value is 1 (single line). A value of 0 means no limit
// if the height of the text reaches the # of lines or the height of the view is less than the # of lines allowed, the text will be
// truncated using the line break mode.
@property(nonatomic) NSInteger numberOfLines;
// these next 3 property allow the label to be autosized to fit a certain width by scaling the font size(s) by a scaling factor >= the minimum scaling factor
// and to specify how the text baseline moves when it needs to shrink the font.
@property(nonatomic) BOOL adjustsFontSizeToFitWidth;         // default is NO
@property(nonatomic) BOOL adjustsLetterSpacingToFitWidth NS_DEPRECATED_IOS(6_0,7_0); // deprecated - hand tune by using NSKernAttributeName to affect tracking
@property(nonatomic) CGFloat minimumFontSize NS_DEPRECATED_IOS(2_0, 6_0); // NOTE: deprecated - use minimumScaleFactor. default is 0.0
@property(nonatomic) UIBaselineAdjustment baselineAdjustment; // default is UIBaselineAdjustmentAlignBaselines
@property(nonatomic) CGFloat minimumScaleFactor NS_AVAILABLE_IOS(6_0); // default is 0.0
// override points. can adjust rect before calling super.
// label has default content mode of UIViewContentModeRedraw
- (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines;
- (void)drawTextInRect:(CGRect)rect;
// Support for constraint-based layout (auto layout)
// If nonzero, this is used when determining -intrinsicContentSize for multiline labels
@property(nonatomic) CGFloat preferredMaxLayoutWidth NS_AVAILABLE_IOS(6_0);
@end

Label 常用的属性以及方法

- (void)viewDidLoad
{
    [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
    
    // 创建UILabel
    UILabel * label = [[UILabel alloc] init];
    
    // 设置label.frame
    label.frame = CGRectMake(0, 100, self.view.frame.size.width, 40);
    
    // 设置文本内容
    label.text = @"程序创建的label";
    
    // 设置文本居中
    label.textAlignment = NSTextAlignmentCenter;
    
    // 设置字体颜色
    label.textColor = [UIColor redColor];
    
    // 设置字体大小
    label.font = [UIFont systemFontOfSize:14];
    
    // 添加至视图中
    [self.view addSubview:label];
    
}

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