ios UILabel簡單記錄

一 UILabel

1.左右對齊：textAlignment

//水平居中對齊  
  [_textLabel setTextAlignment:NSTextAlignmentCenter];
//最後一行天然對齊
    [_textLabel setTextAlignment:NSTextAlignmentJustified];

2.字體：font

3.行數：numberOfLines

//0不限制行數
    [_textLabel setNumberOfLines:0];

4.陰影顏色：shadowColor

   陰影偏移值：shadowOffset

    [_label setShadowColor:[UIColor purpleColor]];
    [_label setShadowOffset:CGSizeMake(1, -1)];

5.換行模式：NSLineBreakMode

    [_textLabel setLineBreakMode:NSLineBreakByWordWrapping];

經常使用：

  UILineBreakModeWordWrap = 0, 
  以單詞爲單位換行，以單位爲單位截斷。 
  UILineBreakModeCharacterWrap, 
  以字符爲單位換行，以字符爲單位截斷。 
  UILineBreakModeClip, 
  以單詞爲單位換行。以字符爲單位截斷。 

實例：文本瀏覽器的簡單應用

@interface ViewController ()
            
@property (nonatomic, strong) NSString *contentString;
@property (nonatomic, strong) UILabel *textLabel;
@property (nonatomic, strong) NSMutableArray *eachPagesRangeArray;
@property (nonatomic, assign) NSInteger nowRangeNumber;

@end

@implementation ViewController
            
- (void)viewDidLoad {
    [super viewDidLoad];

    self.eachPagesRangeArray = [[NSMutableArray alloc] init];
    
    _nowRangeNumber = 0;
    [self initDataSource];
    [self createLabel];
    [self calculateEachPageRangeWithFont:[UIFont fontWithName:@"Menlo" size:15]];
}

- (void)initDataSource{
    //設置背景
    UIImageView *bgImageView = [[UIImageView alloc] initWithFrame:self.view.bounds];
    [bgImageView setImage:[UIImage imageNamed:@"djfoj"]];
//    [bgImageView setContentMode:UIViewContentModeScaleAspectFill];
    [self.view addSubview:bgImageView];
    
    //讀取文件
    //1.獲取文件的路徑
    NSString *filePath = [[NSBundle mainBundle] pathForResource:@"text" ofType:@"txt"];
    
    //讀取文件的內容
    self.contentString = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
    NSLog(@"%@", _contentString);
    
}

- (void)createLabel{
    //建立顯示文字的Label
    self.textLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 30, 300, 440)];
    _textLabel.text = @"點擊開始閱讀";
    [_textLabel setLineBreakMode:NSLineBreakByWordWrapping];
    [_textLabel setTextAlignment:NSTextAlignmentJustified];
    [_textLabel setTextAlignment:NSTextAlignmentCenter];
    [_textLabel setNumberOfLines:0];
    [self.view addSubview:_textLabel];
}

- (void)calculateEachPageRangeWithFont:(UIFont *)font {
    NSRange range = NSMakeRange(0, 0);
    
    //判斷字符串是否結束
    while (range.location + range.length < self.contentString.length) {
        //遊標移動一個字符
        range.length ++;
        
        //獲取當前這個range對應的子字符串
        NSString *subString = [self.contentString substringWithRange:range];
        
        //計算這個子字符串所佔的高度和寬度
        CGSize bigSize = CGSizeMake(self.textLabel.frame.size.width, 2000);
        NSDictionary *dic = [NSDictionary dictionaryWithObject:font forKey:NSFontAttributeName];
        CGRect realSize = [subString boundingRectWithSize:bigSize options:NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading|NSStringDrawingTruncatesLastVisibleLine attributes:dic context:nil];
//        NSLog(@"%.1f %.1f  %.1f  %.1f %.1f", realSize.origin.x,realSize.origin.y,realSize.size.width, realSize.size.height, _textLabel.frame.size.height);
        if (realSize.size.height > (_textLabel.frame.size.height)) {
            range.length --;
            [_eachPagesRangeArray addObject:[NSValue valueWithRange:range]];
            
            range.location = range.location + range.length;
            range.length = 0;
//            NSLog(@"%@", _eachPagesRangeArray);
        }
    }
    //判斷最後一頁是否爲滿
    [_eachPagesRangeArray addObject:[NSValue valueWithRange:range]];
//    NSLog(@"%@", _eachPagesRangeArray);
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    NSRange eachRange = [_eachPagesRangeArray[_nowRangeNumber] rangeValue];
    
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:0.5];
    [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:_textLabel cache:NO];
    [_textLabel setText:[_contentString substringWithRange:eachRange]];
    
    [UIView commitAnimations];
    
    if (_nowRangeNumber == _eachPagesRangeArray.count - 1) {
        _nowRangeNumber = 0;
    }else{
        _nowRangeNumber++;
    }
}

@end