iOS UILabel計算寬度和高度

一、根據文本計算size，這裏須要傳入attributes

    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(20, 100, 0, 0)];
    label.text = @"12331afaa我是誰的誰";
    label.textColor = [UIColor redColor];
    label.backgroundColor = [UIColor greenColor];
    label.font = [UIFont systemFontOfSize:20];
    [self.view addSubview:label];

    CGSize size = [label.text sizeWithAttributes:@{NSFontAttributeName:label.font}];
    label.frame = CGRectMake(20, 100, size.width, size.height);
    // width:193.482031    heigth:23.867188

Method 1

二、富文本計算size

    CGSize size = [label.attributedText size];
    label.frame = CGRectMake(20, 100, size.width, size.height);
    // width:193.482031    heigth:23.867188

Method 2

三、經過UIView的 sizeThatFits

    // 在單行文本的狀況下，參數size設置多少都無所謂，因此裏傳了CGSizeZero
    CGSize size = [label sizeThatFits:CGSizeZero];
    label.frame = CGRectMake(20, 100, size.width, size.height);
    // width:193.500000    heigth:24.000000
    
    // 可用此方法計算高度
    label.text = @"ABCDEFGHIJKLMN";
    label.numberOfLines = 0;
    label.textAlignment = NSTextAlignmentCenter;
    CGSize size = [label sizeThatFits:CGSizeMake(15, 0)];
    label.frame = CGRectMake(20, 100, size.width, size.height);
    // width:15.000000    heigth:334.500000

Method 3